DETROIT (WP) - Moments after hearing about the L.O.L. Surprise! Big Surprise on a Chicago radio station, Ms Crystal Lessner was on the hunt for the popular - and increasingly sold out - toy. But first, she had to figure out what it was.

She logged on to YouTube, where a 24-minute video clued her in.

The US$69.99 (S$95) toy is quite simple: a dome-shaped plastic case filled with 50 surprises - four dolls, along with accessories, clothing, charms and other knick-knacks. But much of the appeal is in its slow reveal. It can take hours, purchasers say, to peel away the toy's layers and figure out exactly what is buried inside.

Watching that process unfold has become a pastime in itself, and there are thousands of L.O.L. Surprise unboxing videos on YouTube. One, a 13-minute video of a woman opening the Big Surprise, has been viewed 6.1 million times since it was posted on Sept 30.

"I knew it was going to be a challenge to find one," Ms Lessner, 36, said. "But I was determined to be a cool mum for the first time in my life."

L.O.L. Surprise! dolls - which stand for Little Outrageous Little Surprise - have become an unlikely blockbuster hit in an era of high-tech, movie-inspired toys.

Released six weeks ago, it is sold out online at Target, Walmart and Toys R Us and is commanding 10 times its asking price on eBay.

The toy, industry insiders say, is one of the first to be both inspired by and created for an era of YouTube, Instagram and Snapchat.