1x18 - Three's a Crowd

Jack's old friend from his Three's Company days, Larry Dallas, invites Jack to a swinging party he's throwing. When Vicky finds out about the party, she says that she doesn't mind, but really wishes he wouldn't go because his former girlfriend, ""Greedy"" Gretchen will also be there. ""Greedy"" Gretchen puts the moves on Jack just as Vicky arrives