From Angry Asian Man, another suspect educational product. This one claims that kids playing “Rock Paper Scissors” in Beijing would say “Ching! Chang! Pok!” Allegedly in Japan they shout “Ishi! Hasami! Kami!” [rock scissors paper].
I’ve heard “Shitou jianzi bu!” in Mandarin and “Jan ken po!” and “Gu choki pa!” in Japanese. Asked a couple of Chinese American kids who said they’ve heard “Shitou jianzi bu!” but they say “Rock paper scissors shu!” (maybe “shoot”?). Interestingly, “bu” means “cloth.”
Of course there are probably two hundred plus Chinese languages. But I still kinda doubt this one.
How do you play “Rock Paper Scissors”? And what do you say?
Resist racism 
I say “jiandao [scissors] shitou [rock] bu [cloth]”, and you throw your sign on “bu”. It probably ends on “bu” because “bu” has a falling tone so it gives the phrase a nice rhythm.
“Ishi! Hasami! Kami!” This is baloney.
My Japanese is rusty, but I remember playing with words closer to this: “Jan ken po!” (Although I remember it as “pun” not “po”). And then, if there was no winner, something like “Ai ko desho!” (I spoke pretty good Japanese but I never understood what the words actually were in this game or what they meant, so what I’ve just written may be complete butchery.)
Also, in Japan, there was a second part to the game if you got down to two players who tied. Persons A and B would face one another, and then Person A would point right or left, and Person B would have to turn their head the opposite way, but quickly. And that would go on until Person B looked the wrong way.
I have very fond memories of playing that with friends in Japan.
Japanese: Saisho wa guu! Janken pon!
And if you throw the same sign, follow up with, “ai ko de sho!”
granted, I only speak English, but whenever we played Rock Paper Scissors, we didn’t say anything. Or if we did we’d just say “1, 2, 3” or “1, 2, 3, go”.
Ever since seeing South Park, tho, I call it rochambeau-lite.
In Hawaii we say “Jan Ken Po, Ai Kono Sho” or in pidgin “Junk An’a Po, I Canna Show”.
In Korean it’s “Ka-wi, Ba-wi, Bo.”
Dynamite. Always go with dynamite at the end.
So far my research has revealed no Chinese speakers who say “ching chang pok.” Most said “jiandao shitou bu” as Andrew mentioned. And no Japanese speakers who say “ishi hasami kami.” “Aiko desho” reportedly means “It’s a tie.” I heard a corruption of that which sounded like “I kono ho,” similar to m.
I did see a video of two white kids making ching-chong sounds and gestures before playing.