Je te tiens, tu me tiens, par la barbichette;
Le premier qui rira, aura une tapette!
"I hold you, you hold me, by the chinny-chin;
The first to laugh, will have a little slap!"
A French kids' game. Two children face each other eye-to-eye and grab the other's chin. Whoever laughs first gets a (playful) slap on the cheek. Barbichette literally means "goatee", but children use it much like "chinny-chin" is used in English. The word tapette can mean "flyswatter" or "carpet beater," but because it is also a vulgar word for a homosexual, many children have learned the rhyme with the word giflette ("little slap") instead. The last "-te" of each line is pronounced, unlike standard spoken French, but common in French poetry.
I've always heard it with a specific meter:
1 & 2 3 & 4 5 & 6 & 7-& 8 (*)
Je te tiens, tu me tiens, par la barb- i- chet- te
Le pre- mier , qui ri- ra , au- ra une tap- et- te
A quick search on the Internet informs me that there's another line that's sometimes said: de nous deux ("of us two") is sometimes inserted between premier and rira, although I don't know how that works into the meter.
* Beat notation: each number is a down beat (eighth notes in this case); the ampersands are the up beats. It's a common drum notation; see 1E&A. The "7-&" means the syllable is held until the up beat after 7.