She didn't get it at first, but apparently to stay home in Korean is 방곡 which the student had wrongly translated into English phonetics bangcock. Good times.
This situation was actually reversed on me later in the day when I told my grade 3's 'Don't cheat' to which they all broke into fits of laughter and shouted 'Dongchim Teacher?'
Dongchim= Students clasp their hands together, pointers out and stick those two delightful fingers up your bum (they do it to just about anyone and everyone and no one gets angered!?)! Pretty hilarious as they were all standing in a line at the time with their backs to one another...
'Mum, Corey Teacher told us all to dongchim each other today, Corey Teacher's pretty cool.' At least to Korean children I would be!