My dad used to make me practice kanji so I wouldn't forget it, so one day I was practicing in class and thought it would be funny to describe a dirty scenario between two teachers at the school, but when my History teacher noticed I wasn't paying attention in class, he took my notebook and after eyeing over it for a second started to read it aloud in English.
Sucks when you don't realize your history teacher for 3 months had taken like 4 years of Japanese in college. :c