Cyndi Irresistible caught a body inflation quickie the other day while watching Battlestar Galactica and let me know.
Apparently it's a man in an elevator, alone. A bunch of people crowd into the elevator all around him, so he rolls his eyes, holds his nose and blows. His body (and face) swells up and pushes everybody out of the elevator so that when the doors close, he's all alone again. It ends with the word "IF" on the screen, which then merges into the Sci-Fi channel logo.
Watch for it...I will!
Found it: Sci-Fi
It's the one titled "Pufferman"