Y'know, slowly back out of the alley, or, if you're a male and wanting your rectum to remain a one-way system, the wall. Wave your hands gently, like calming a wild animal and soothingly say 'there, there.' Maybe stroke their nose, pat their head? Perhaps wave a tasty treat in front of their nose, or distract them with a yo-yo.
Didn't you get the memo a while back? Young women are supposed to fend off rapists using the pair of scissors they keep in their purse. Anything to avoid having to use an evil, evil gun.
Oh my if there is no god, he will invent himself just so he can send you to hell on the express train!
In Anna's case, her vagina's pungent odor is an effective rape deterrent. Nothing like skunk mixed with rancid Long John Silver's to discourage Mr. Rapey.