You might hear it said in examination halls as students encourage one another.

But the expression "add oil!" - a literal translation of the Mandarin term "jia you" - has been deemed to have become so universal that it is now an official entry in the Oxford English Dictionary (OED), complete with exclamation mark.

The discovery was made by Associate Professor Hugo Tseng from Taiwan's Soochow University, who wrote a column about his finding in Hong Kong's Apple Daily on Sunday.

"To directly translate 'jia you' into 'add oil' - this is a form of Chinglish that many English teachers will correct. But it has become popular to the point that the OED has accepted it and recognised its place," he wrote in Chinese.

The entry describes the phrase as being of Hong Kong English origin and defines it as "expressing encouragement, incitement or support", as in "go on! go for it!". It includes the corresponding Mandarin "jia you" and Cantonese "ga yau" in its explanation, saying the term references "petrol being injected into an engine".

Several sources suggest that the expression originated as a cheer at the Macau Grand Prix in the 1960s, according to an editor's post on the dictionary's website in May 2016. The Straits Times reported in the same month that 19 Singlish terms had been added to the OED, such as "blur" (slow in understanding) and "lepak" (to relax, hang out).