Top deck...
Refers to the male
genetalia, where half is lighter than the other half.Usually
the balls and half the shaft is brown or darker and the top is lighter, like a Cadbury Top Deck chocolate.
Also applies to when the whole of the man's
genetalia is darker than the rest of his body.
"
omg girl, I made out
with him finally and he has a top deck"
He looked at his dick and realised he was a top deck
He was white as snow but he was
swinging the top deck