- Charlie Day (Charlie Kelly)
- Glenn Howerton (Dennis Reynolds)
- Rob Mac (Ronald 'Mac' McDonald)
- Kaitlin Olson (Dee Reynolds)
- Danny DeVito (Frank Reynolds)
It's Always Sunny in Philadelphia — S5E10
Episode: The D.E.N.N.I.S. System
Air Date: 2009-11-19
Runtime: 21 min
Overview
Dennis reveals his foolproof system for seducing any woman to the rest of the gang, but they don't grasp the concept.