Im just that bitch means: im the irony queen and yall should be friends with me or you guys are my bffs and your my bitches, im full of sarcasm and crazieness and i am just that bitch.
Your bffs: your kinda crazy
You: well im just that bitch
Or
A person you wanna befriend: your super nice and sarcastic
You: well im just that bitch.