intimidate wild female to stay away from his clutch of eggs!

Because he is really, really bad at flirting.

Is he also being flirty? I think he's trying to set up a casual NSA arrangement with you. He's letting you know that he's only so available

he probably thinks you're hitting on him.

...because he has a gf.

Stop with the crazy eyes, you're freaking him out

He’s not into you