Jan-Ken-Hoi!
During my school day I'll see it played to decide which student gets the hardest part in a role play, which student has to go first, which student clears the desks after lunch etc. Occasionally on the news you will see that a judge might use it to settle some ridiculous dispute.
But more recently, "alternative janken" has come into play. Since the pioneering days of those on the Nathan Barley show with their "Cock, Muff, Bumhole" moves, numerous alternatives have sprung up. One South African ALT introduced me to "Tinfoil, Cat, Microwave", while another South African ALT introduced me to "Gun, Grass, Goat".....
The other night, during an alcohol induced wave of 飲speration*, we invented "Smoke (or toke, we're undecided), Coke, Poke". Can't quite decide what wins over what though.....
*It's only clever if you understand that 飲 means to drink, and is pronounced "in".

