Smegma: The foul, cheese-like sebacious substance that grows beneath the foreskin or beneath saggy tits.
"I picked up dat bitches titty and it looked like a duck-butter sammich.
A film in your ass thats so thick you can spread it like butter
Man i havent showerd in a few days and i got some sick DUCK-BUTTER going on all up in my butt! wanna see?