Space Thing.

A man is in bed reading Sci-Fi mags, and his wife seduces him. He then falls asleep, and the rest is his dream. He is from an alternate world, and disguises himself as an alien, then boards their ship, to keep them from attacking his planet. The captain is a woman, who has two lesbian encounters with her crew, and whips one of them for trying to have sex with our hero. All of the women are anxious to seduce our hero, as the other two men on the ship are not very exciting. Our hero forces a landing on an asetroid (actually the outskirts of Palmdale, California) and everyone runs around topless and has sex. He then blows up the alien ship in the worst special effects explosion.