Lemon Line
A "skinny white border" applied to the outer edges of a photographic print before mounting on a black matte board, named after the professor who never fails to suggest it as an improvement.
"Oh snap, I accidentally cut off the Lemon Line!"
"I guess you'll have to reprint now."
"I wouldn't hand that in without a Lemon Line."
"I guess you'll have to reprint now."
"I wouldn't hand that in without a Lemon Line."