"Hot Wet Pussy Operation." Describes a situation in which a male will willingly place his penis in an appropriate vessel, typically the vagina, and thrust accordingly. Also see hooking up, getting laid, beat da puss up, tap dat ass, broner, brojob, brohansebastianbach, bromance, brovaries, and fornication.
Naturally, the word "operation" was added to ensure that bros using the term would not feel a decline in masculinity upon completion of said task.
Dude, you get any action last night?
Affirmative, HWPO complete man!