When a girl that has a boyfriend or has no romantic interest in you says you are cute or adorablelike a kitten or a similar cute, small, and furry animal.
It's similar to being put in the friendzone but better.
Girl with platonic feelings: Aw, you're so adorable.
Boy with a secret awkward crush: How so?
Girl with platonic feelings: Like a kitten or lemur!
Boy with a secret awkward crush: Uh...hah...? Thanks...
Interlocuter: Oh no! You've been kittenzoned!
Boy with a secret awkward crush: At least we're friends and I'm cute?
One who displays loser-like qualities; one who sucks at pretty much anything; one who pets kittens.
Patricles: Dude, you just got killed 5 straight times in Halo,you are such a kittenpetter.
Michelle: You know what, you're a black kitten petter!
Crowd: oooooo, that's the worst kind.
Kittenpetter easily takes the place of the word "noob."