Bukkake is typically when lots of guys all jizz on one chick. It is claimed to originate
from Japan when a woman was unfaithful, she was bound naked in the center of
town and all the guys jizzed on her. It was first introduced in porn by the
Germans, of course, and was also modified to a tamer version of just
shooting on a girls face at the end of a scene, which
is now a fairly common practice.