There is something that I have never been able to understand. It is wrong for a poor person to stop people in the streets to ask for money. That is begging. It is against the law.

But give a tin to a kid in a school uniform, tell him to ask pedestrians for money on behalf of that poor person, then that is okay. That is not begging, that is flag day.

It is Saturday, March 19, 9am and I am picking up my tin and that is no time for questions.

Recently, I had become so sick of having a tin waved at me that I stopped giving. My sticker-free shirt became a badge of defiance. I would tell myself that something about that child with the tin looked fishy, or his shirt was not tucked in properly, or that I didn't need a sticker to prove that I was a good person. I was angry that Saturdays came with a walking-around tax.

So when it was suggested that I try holding a tin for a few hours, I said fine. Maybe I could work out my flag day guilt and anger issues. Or at least, I could punish myself for being mean to kids.

The name "flag day" most likely came about because charities used to sell pins with paper emblems. We have stickers now, which are less dangerous but which cause more confusion for non-Singaporeans because they think the phrase refers to a day when we go mad for fluttering banners and national colours flying patriotically in the breeze.

A recent report in the newsletter of the American Association of Singapore said that "seeing thousands of people spread out across the city collecting money in tin cans on the same day sure seems uniquely Singaporean". It sure does. There is some very Singaporean grumbling about flag days, too, if you look online.

At least I won't be alone. Today, I will be part of a 7,000-strong army. We will be collecting for the charity Hope worldwide (Singapore) and St John Ambulance. Most of the tin-carriers are St John cadets, Hope worldwide volunteers and students doing it as part of their schools' Community Involvement Programme.

There is a problem. It looks to me as if all 7,000 of them are here in Bedok Central, my assigned spot. There are clumps of collectors at the bus interchange and MRT station. Teams are stationed at corners of blocks, ready to pounce on shoppers. Roving herds of students pick off the remaining un-stickered. Yikes. Where could I go?

Then I spot a lone she-wolf and her cub. Outside a McDonald's restaurant are Ms Stephanie Siau, 44, and son William, 10. Their can-fu is superb. People are halting in their tracks and putting in the money - the much sought-after stop and drop. The administration executive is a volunteer from the Central Christian Church, which founded the the local branch of Hope worldwide, an international Christian charity.

I ask her advice. Location is key. There are rich pickings around wet markets outside of HDB central zones, she suggests. These areas are less saturated with volunteers. But as a male, not in uniform and working alone, I shouldn't try it. "People won't trust you," she says. They are scam-wary. She is using one of her own top tips: Rope in a child to do the stop and the drop will follow.

William is a pro. He steps into the path of adults three times taller than he is and unleashes a grin so big you can see it from space. You would have to be a monster to say no to that face.

The secret is the stop because once a walker's momentum is broken, you have his attention. But he will be irritated. Make the obstacle a cute kid and that irritation is defused. Have an adult interrupt his walk and he is as likely to punch that adult in the face as give him money.

Ms Siau lays out the game plan. Once that person stops (however you do it), make eye contact. Smile. Say "Hello sir/madam, could you help senior citizens' and children's programmes?". If they drop in money, say thank you. If they do not, say thank you. Leave them with a good impression because they might give to the next collector they see.

Some pedestrians ask what charities we represent. Hope worldwide is not as well-known as, say, YMCA or SPCA. Mum helps William when he is asked that question. She tells me that parents with kids are the best givers. She is proven right, except in one case. There is a dad who practically tells me to get lost, in front of his young son. "Hey," I want to tell him, "in a few years, your son will be in my place. He's going to remember what you said."

I hang around with Ms Siau and William. She graciously lets me practise my skills on many passers-by. By 11am, I have given away about 30 stickers. Many have popped $2 notes into my tin. I hand it in at the collection centre and go to Orchard Road to pick up the next one.

Next stop: Outside The Heeren building. There is a church volunteer there, as well as many student collectors roaming freely but the corner is large and I put my stake in one end. People walk quickly, so I shorten my pitch to "hellosircouldyoupleasehelptheORPHANS?".

I stress the last word. I don't have William's cuteness, so I have to use guilt. My unspoken message: Why won't you stop? Do you hate orphans?

I make a couple of observations. I get the most brush-offs from people who look as if they would be in the best position to give. Nice clothes equal bad, bad people. Pedestrians have different ways of saying no. Some say "No, thanks," as if I were handing out free cookies. Some give me a "talk to the hand" palm-up gesture. Most just walk around me as if I were a pothole.

I recognise a former colleague out with her boyfriend and after saying hi, they hurry on, their finances intact. Odd. Some men reach into their pockets but do not stop walking, forcing me to tag along with my tin outstretched. Were they taking part in a very slow race? I notice people on Orchard Road are less generous overall. They give coins. In Bedok, there were more $2 notes.

One young woman has shopping bags in both hands. No problem. I hold her purchases while she gets her handbag out. An elderly British couple, just off a cruise liner and on a quick look around town, give a donation then stop for a chat with me. Nice people like these are an unexpected bonus.

At 1pm, it is the end of the morning shift and I turn in my tin. I have given out 10 stickers after about 1-1/2 hours of canvassing. Not a great score but among the donations have been some extra-generous people. A disabled man, with a crutch under each arm, dropped in $10 after asking me a few questions about the charities. One dad gave money to all three of his kids for my tin and another man who already sported a sticker gave again. A tourist with a Scandinavian accent popped in the roll of $2 notes so thick it needed a sharp push.

"Wow, that's very nice of you," I said.

He looked at me, puzzled. "That is very little," he said, then walked away.

In total, the two charities collected about $300,000 that Saturday. Flag days, whether you like them or not, work. There are 62 of them listed on the schedule this year, one for each Saturday and on Wednesdays during school holidays.

Who gets to collect is determined by a ballot organised by the National Council of Social Service, which also lays down the rules for the street collection. This includes how tins are consolidated, checked and opened, according to a council spokesman. Compared with other ways of raising money, flag days are less of a hassle and incur less cost to run.

By 1pm, almost everyone I see on Orchard Road had been, as I like to call it, snagged, flagged and tagged.

I might still get a little annoyed the next time a tin appears under my nose. A few hours of can-carrying is not going to change me that quickly. I have decided that I might cheer myself up if I think of it this way: Anyone who has a roof over his head and three meals a day needs to give, sooner or later.

Think of flag-day collectors as a means of bringing charity to you, saving you the trouble of looking for it. Now, isn't that worth stopping for?