It’s not her fault, some dweeb (Fluttershy) fell over and latched onto her shirt and skirt and ripped them off comically.
Is she flipping off Fluttershy? Of course not! It was an accident!
She’s flipping off the dorks cat-calling her.
“Like I’m the first pair of tits you’ve ever seen. Wait, on second thought, considering what a loser you are, yeah, I probably am. Fuck off!”