Setting: America (happy fun land!)
Is it even remotely possible to do this:
Without breaking an arm, setting your hair on fire or otherwise Doing Bad Things to Yourself or should I just leave this particular stunt in the world of anime physics?
The character attempting this isn't really trying to hit anything; she's more interested in the intimidation value of "I HAEV A GUN AND I CAN SHOOT IT UPSIDE DOWN".
She also has a rifle instead of an outrageously huge handgun and is holding onto it with both hands, if this changes the general plausibility.
ETA: I've googled "firing guns upside down" and gotten that it won't jam an automatic and makes them awkward to handle, but not "firing them over the shoulder and not hurting yourself".