A German Shotgun, or German Shotty, is similar to a shotty that most potheads are familiar with, however, instead of placing a blunt backwards in ones mouth and blowing it into someone else's mouth, you instead use a straw to blow the smoke into the recipient's asshole. Another participant then comes and sucks the smoke out of that asshole for a powerful hit.

A casual invitation / threat used by an individual that is not afraid of fucking someone up.