a fatty - A huge, but nice, butt. Or a huge joint, like the size of a

A huge, but nice, butt. Or a huge joint, like the size of a donkey.

She's got a fatty, it's like she was born with a butt made of bricks.

He smoked a fatty, it was like he was trying to kill himself.

That joint was a fatty, it took him ten minutes to finish it.