I am pleased today to introduce the old Japanese children's game, "Watch your butt" (お尻の用心).

How to play

1. Pull the rear hem of your kimono forward through your legs. Tuck it into the front of your obi.
2. Frolic with some friends—close friends—singing the "Watch your butt" song below.
3. When you see a chance to pull someone's kimono back through their legs, flip it up and expose their behind, do so. Meanwhile, be careful not to be so shamed yourself.

Yeah, that's it.

The "Watch your butt" song

O-shiri no yōjin, koyōjin
Kyō wa nijūhachi-nichi
Ashita wa okame no dango no hi

Watch your butt! Better take care!
It's the twenty-eighth today
Tomorrow's turtle dumpling day

This is the main version recorded in OBARA Akio's Nihon no warabe-uta (日本のわらべうた, "Children's songs of Japan"), although he notes that the details vary from prefecture to prefecture. Perhaps, he muses, each regional version preserves a unique local bottom-related custom.

It seems unlikely that this game began as mere naughtiness... the mysterious specificity of the lyrics and the brazen exposure of the bottoms of others, an act not usually permitted, suggest that it evolved from some old folk custom or ritual.

Here are a few variant lyrics, also courtesy of Obara:

• It's the twenty-eighth today/ Watch your butt, better take care (Late Edo)
• It's the twenty-fifth today/ No butt-flipping allowed! (Kyoto)
• It's the Day of the Ox today/ Got your butt, pardon me (Wakayama)
• It's the fifteenth today/ I wanna see a lot of butts (Shimane)
• Guard house, guard house/ Pull in your butt, guard house (Aomori)