1) An ugly guy that male metro-sexuals hang out with to increase their chances of getting laid.
(Unlike hot girls' relationship with their respective ooks, guys are emotionless, vigilant sexual pragmatists, who don't really care if the oonk gets laid or not, therefore, oonk has two connotations.
2) A (optionally) ugly or pathetic guy that fiercely heterosexual, albeit socially inept and sexually underexperienced hang out with to make fun of in front of girls, because, in their warped minds, they think that girls like assholes, and they will get laid. Certain girls do like assholes, but they think that guys who pretend to be assholes to get laid and are truly decent people are fucking pathetic, and no matter how empty they themselves are, they are true. That's pathetic.
Jake: Fuck that kid, he's just our oonk, you know.
Sally: Wow, you're so brilliant.
Jake: Suck me.
Sally: No. Okay. You look like my daddy *slurp slurp*.
A force of nature that is unpredictable and uncontrollable.
Person One: I'm facing an oonk.
Person Two: Run man, run.