The Correct Answer Was Two Fingertips But I like Yours Too

During yesterday's third grade class:

Shuting: Does anyone know what letter this is?
3rd grade class: B!
Shuting: Say that again?
3rd grade class: B!

[repeat. Shuting then tests them by pointing to A, then B and asking them to shout which letter it is]

Shuting: And if you look at the shape of B, what does it look like?
3rd Grade Boy: A big butt!

And who said humor was culture specific?