The feeling of being "Peterbummed" is usually caused by a friend that either cock blocks, punches you in your "jewls", an erectile disfunction, a man named peter being bummed out, or a situation where you're just not spunky enough when the time to perform arises.
A variant of douche-bag, a person who is overbearing yet amicable. The person is often polarizing, some love and others hate at first introduction; reference to Victoria BC Canada 2008.
Caroline, I like you. But your boyfriend, Peter, has shocked me. I actually have to create the term 'peterbag' to describe him. Fuck.