Japanese Snot Eaters

Checking out baseball practice on my way home one day, one of my normally quiet 7th graders starts talking to me a bit--being a 7th grade boy, of course, he has some typical boy questions.  For instance:

Him: "What's this?" while pointing at his nose.
Me: "Nose?"
Him, in Japanese now, "no, [Japanese word I haven't learned]."
gestures at something reminiscent of picking your nose.
Me: "..Snot?"

"Su-not!" he giggles.  

He points at his friend.  "You are 'snot!'"  His friend gives him a quizzical look, while Yuu* (the first boy) repeats the accusation, cracking up.

He turns back to me.  "What's [a bloody nose**?]"
My translation is too long for his liking, so he immediately moves on.
At this point a 9th grader, Daijiro, has come over to supervise.
"What's [poop?]"
Me (faux innocent): "I don't know."
Yuu squats, and gestures from his butt.
At this point Daijiro interjects telling him to stop it.  ("You are a bad man," Daijiro scolds, but being a lowly 7th grader Yuu needs a translation to get the insult.)

I of course refuse to tell him anything more at this point, seeing what he's already done with the little I've given.  Yuu tries to get a couple more perverse but typically boyish words translated, along with hilarious gesticulation--I've never had as much fun playing dumb as when he was gesturing at [from] his crotch looking for confirmation of what it's called while some two dozen of his classmates looked on cracking up. Eventually he gives up and goes back to his old ways.

Yuu: "This boy likes snot. He eats snot!"  "You are su-NOT!"

I'm glad I'm still making friends even with the end so close.

(*He spelled his name as "You," using the well-learned English pronoun in his farewell note.  Adorable. 

**For the record, a bloody nose is a sign of perversion in popular media here--blood's all rushing around so much that the nose gives out).