Steve Guttenberg Gets a Burst of Sex, in "Cocoon" (1985)

Any man would love to get physical with an alien that looks like Tahnee Welch, but unfortunately her character’s species doesn’t have sex the way humans do. Still, Steve Guttenberg looks pretty satisfied with the way she does it to him, apparently tossing a burst of light and energy, or something, at his chest. The only problem is it’s clearly one-sided. Then again, we never do find out if what we’ve seen is just foreplay.

Kim Basinger Learns About Sex, in "My Stepmother is an Alien" (1988)

If your mission calls for you to travel to Earth and marry a human, naturally you’re going to be expected to consummate the marriage. Fortunately for Kim Basinger’s sexually ignorant alien, her purse-dwelling, phallic-looking companion can project instructional films and dispense "Debbie Does Dallas" videotapes. In no time, Basinger is a an expert on the subject, or at least in the ways of turning on hubby Dan Aykroyd — and probably way too many young boys in the audience of this seemingly family friendly PG-13 movie. The scene cuts just before the actual sex begins, but it may as well have kept going. It couldn’t have gotten anymore explicit than this. And we’re pretty sure Aykroyd has already come by the end of this clip, anyway.