This was from nearly 20 years ago. Penn was still fat. The series was called "Bullshit!" and was a Showtime special series that ran for several seasons. This was well into the series, I recall.
Their episodes on porn, recycling, stranger danger are also really good.
I couldn't stop laughing at the one on mowing lawns. Of all the stupid bullshit ideas, and it was hilarious.
LOVE Penna and Teller. If you go to their Las Vegas show they will take a picture with every single audience member that wants to hang around long enough!