1) A "sketchy" (creepy/shady) person who watches from a distance but scarcely moves, similar to how a hippopotamus peers out of the water with only it's eyes but remains still.
2) A not-so-subtle way of alluding to someone's sketchiness.
1) Jim- Anyone else notice the guy over there peering over his menu?
Sally- Yeah.
George - Yeah man, he's been doing that for like an hour. What a f***ing sketchopotamus.
2) Billy- I'm not so sure I trust that Frank guy you've been hanging around with, Lisa.
Lisa- What do you mean? He's a total sweetheart. Just yesterday, I ran into him at the supermarket and then AGAIN at the dry cleaner.
Billy- Let me just put it this way: if Frank had a favorite animal, it would be a sketchopotamus.
When a chick cockblocks your bro from hanging out with you. Both guys must be heterosexual so it's not an actual "cockblock," unless both are homosexual, in which it is.
You: "Dude, lets go play frisbee!"
Bro: "Yeah, bro!
Chick: "Aw, baby come stay with me!"
Bro: "Alright, see ya later, dude."
You: "Aw, man, I just totally got bro-blocked!"