A really dumb guy with a big dick or a really big dumb guy who still leeches off of his parents or a guy with no ambitions.
Justin is such a meat wad he amazes me how he can just do nothing.
Wow your boyfriend is such a meat wad at least he's good for one thing!
Meat wad: "Hey Dad I need to borrow some money for rent because I spend my pay check on drugs. No I mean beer."
(He never pays his dad back because he doesn't care. Does it when he needs moany)