The caption of a photo of a young boy glaring -- for lack of a better description, the face is impossibly funny -- at a slightly older girl holding what appears to be a freshly caught fish. Colloquially, the phrase can be used in reference to a woman who has taken something, or just as a general exclamation.
(Retelling an altercation with one's girlfriend)
A: ...and so she just took that shit from me. Man, was I pissed. Fuckin' bitch stole my fish.
B: You gotta stand up for yourself, man. Tell ya what, no fuckin' way I let that bitch steal MY fish.
(or, alternatively... while playing Madden)
A: Oh, FUCK, bitch stole my fish!
B: That's right, bitch, pick six.