If you ask a die-hard fan when It’s Always Sunny in Philadelphia reached its peak, they won’t just give you a year—they’ll give you a system. Specifically, the D.E.N.N.I.S. System .

One of the funniest (and most depressing) episodes of " It's Always Sunny in Philadelphia" is season 5's "The Gang Hits the Road," The Gang Hits the Road The Waitress Is Getting Married

Getting Weird with It: Why Season 5 is the "Platonic Ideal" of Always Sunny

Season 5 of It’s Always Sunny in Philadelphia is widely considered the moment "The Gang" truly perfected their brand of depraved, high-concept chaos. Premiering in 2009, this season saw the show transition to a 16:9 widescreen format and cemented many of the series' most iconic tropes.