from https://www.urbandictionary.com/define.php?term=Dumpster+Party

(1) The act of throwing a dead person, typically a woman, into a dumpster.

(2) A gathering of a group of gay men in an alley next to garbage dumpsters for the purpose of engaging in a homosexual orgy. One or more of the men often lean against a dumpster while giving or receiving a sexual move. Dumpster parties often occur late at night in alleys next to bars or fast food restaurants.