Refers to something obscenely obsequious or pretentious, as in something done to suck up to or show off for someone, especially to the detriment (and at least annoyance) of others. Usually an exclaimation used to sum up one's feelings about a series of events or an experience as a whole.
(Jenny) Can you believe the way Lisa goes up to the professor every day after class to fawn over him?
(Laura) I know, it's disgusting. Pukefest!