Knobcheese, smegma, remains of 'joyfluid' or sperm on a man's penis. Usually caused by bad hygene or uncontrolled loss of pre-cum, when not being able to clean it right away.
Because it's white and smelly like cheese, Brie is a good name for it.
Yuck! Go wash your pee-pee, there's Brie all over it!