When a person masturbates in a concealed area like an alley, then rushes out to ejaculate on an unsuspecting passerby.
It can be done from a ceiling, a window, or the street. So long as it involves someone unexpectedly getting spermed on, it's sperm sharking.
Guy 1: Melody told me she was sitting in the park the other day, when this homeless guy came out of nowhere and jizzed on her clothes.
Guy 2: Jesus Christ!
Guy 1: Apparently it's called Sperm Sharking.
Guy 2: Why is that?
Guy 1: Cause of the whole unexpected Jaws thing. Du-dun du-dun...
When someone (usually a girl) plans on shacking with someone of the opposite sex, but doesn't want the other person to know she planned on staying over, she packs strategic items in her purse, such as a contact case, make-up remover, toothbrush, maybe even flip flops.
The act of stabbing someone with a shank. Comes from the word shank which is a crude knife usually made in prison, a homemade knife-like weapon usually made from a spoon.