Sweet Throat (USA 1980)

Beth Anna and recently divorced Eric Edwards are hurrying to arrive at an apartment, just gone on the market for rental. Beth irritates EE by failing to stop and help him with a flat tire. So she arrives first and signs the lease, after servicing bldg. supervisor Roger Caine to get a better deal on the rent. Edwards arrives too late, but Beth makes it all right by servicing him too. Both gentlemen comment on what a "sweet throat" she has. The rest of the story is devoted to Beth's BFF Clea Carson having sex scenes of her own, leading to a birthday party for Beth that of course turns into an orgy.