GaGa's BF Pokes Her Face ... With His Tongue

Lady GaGa can't exactly shut her Playboy mouth ... when someone else is exploring the inner confines of it.

Though they were rumored to have split, Stefani Joanne Angelina Germanotta and BF Speedy sucked all sorts of face Wednesday in Hawaii.

BTW -- check out her bathing suit ... even on vaca she's in costume.