Dennis Quaid week continues! Quaid's been shrunk to molecule-size and injected into Martin Short, who drinks Southern Comfort so that Quaid can catch some on the way down. And then they dance together: Short and his microscopic companion.
Innerspace is a strong contender for Dennis Quaid's most bizarre SF movie of all time, although it has plenty of competition. After Quaid is injected into Short, he manages to hook himself up to Short's optic nerve and his eardrum, so he can see and hear what Short sees and hears — and he can somehow talk to Short as well. This allows Quaid to give Short advice on how to "dominate" Meg Ryan — which apparently worked well enough that Quaid and Ryan were married soon afterwards.
The other greatest sequence involves Robert Picardo, the holographic doctor from Star Trek: Voyager, playing an immensely hairy Eastern European fence called The Cowboy, who disco dances in cowboy boots (and sometimes not much else.) Short gets the drop on Picardo and ties him up in the bathtub, then Quaid somehow uses his miniature gizmos to convert Short's face into Picardo's. You know it makes sense.
At least, it makes more sense than a guy who's one molecule thick being able to drink normal-sized liquor, as Roger Ebert gleefully points out.