1. Someone who bases attractiveness purely on looks.
2. Someone just looking to use someone else. See one night stand. Hooking up is also known to be shallow.
3. Not looking to someone's heart. A guy won't date a fat girl because she is not attractive enough, even if she's greater than any girl they know.
"Dude, look at that ass. I'mma tap that."
"Ew, too fat for me."
"She's an absolute bitch, so when I'm done fucking her I'll just dump her hot ass."
"Seriously, how shallow can you get, dude."