Watch As Charlie Day Is Forced to Put Tighty Whities on Danny DeVito (VIDEO)

The cast of It's Always Sunny In Philadelphia stopped by Conan last night, and they brought some pretty amazing footage with them. In this very special behind-the-scenes clip, Charlie Day is forced to help Danny DeVito put on a pair of tighty whities. And when he accidentally puts them on incorrectly, he's forced to start over.

Jesus. Talk about paying the troll toll.

Why would anyone besides a call girl go near Frank Reynolds' Junior and Twins? As Day explained, DeVito is known for his willingness to do whatever a scene requires. But when asked to appear in a scene wearing only tighty whities, he balked, and showed up wearing boxer briefs. When Day pushed him to change, DeVito agreed, but under one condition: Day had to help put them on.

In the name of comedy (and probably in the name of creating a viral video) Day agreed, and the rest is history.

At the 2:15 mark, you can hear DeVito say, 'Don't linger or it's gonna get big.'

Gross. Amazing. But gross.