Funniest mistake made by student as yet

Damn funny...must share, must share.

This is a translation of a Japanese poem done by a second-grade student:

last stanza:
It snows heavily, it hails heavily
Snow and hail, snow and hail
Never stop snow and hail
Dogs are excited and run around a field
And cats hump in a kotatsu (?!!)

Don't ask me where my student got the word from...I NEVER taught him that!!

(Explanatory note: A kotatsu is a Japanese table (with a removable table-top) with a heater underneath. In winter you drape a quilt over the table frame but place the table-top on top, so you can stick your legs into the kotatsu and stay warm and have a normal table too.)