"Dennis Reynolds: An Erotic Life" is the ninth episode of the fourth season of It's Always Sunny in Philadelphia.
Dennis plans on publishing an account of his sexual exploits and ends up in a rehab facility along with comedian Sinbad and "Matchbox 20" frontman Rob Thomas. Meanwhile, Charlie and Dee try on each other's lives for size.
11:00PM on a Monday
- Charlie Day as Charlie Kelly
- Glenn Howerton as Dennis Reynolds
- Rob McElhenney as Mac
- Kaitlin Olson as Dee Reynolds
- Danny DeVito as Frank Reynolds
- Lawrence Mandley as Black Dude
- Cantrell Harris as Orderly
- Rob Khakh as Movie Patron
- Jesse Caron as White Guy
- Roberto Raad as First Comic on Stage
- Alexandra Sceales-Smith as Twin Girl #1
- Tegan Sceales-Smith as Twin Girl #2
- Patrick Walsh as The MC
- The audience member who shouts "Jesus Christ" at Dee when she's on stage doing stand up, is actually Glenn Howerton. 
- There are illustrations in Dennis' memoirs book. Charlie was truly enjoyed them - really hard and very vigorously (like in "The Aluminum Monster vs. Fatty Magoo" episode).
- This is one of the longest episodes of Sunny ever (together with 02x04, 02x10 and 06x11).
- This episode (with production code IP04005) was supposed to contain a scene where Charlie and Dee were stalking the Waitress: here's how Dee learns about Charlie's "stalking notebook", and then she stealing it right BEFORE "Who Pooped the Bed?" (IP04007).
- This is the second time someone's tried to achieve something by pretending to have cancer. However, due to Mac's ignorant execution, it fails immediately.
- We first learned that Frank and Charlie sleep "ass-to-ass" in their bed in the episode "Who Pooped the Bed?"
- The twins Sweet Dee sees in the hallway of Charlie's apartment complex is a reference to Stanley Kubrick's The Shining .
- Dennis will actually attempt to make a movie of his erotic memoirs in the Season 11 episode "Dee Made a Smut Film".
- The movie Mac and Frank see is Three Coins in the Fountain, which has throwing coins into a fountain to make a wish as a major plot point.
- Dennis: (referring to his memoir) Charlie, what the hell were you doing with it?
- Dee: Well, uh, since he can't read, I'm guessing he was masturbating to your pictures.
- Charlie: You know what, what are you doing to me? Why are you doing this? You've been riding me, now your accusing me of things, and you just don't get it. You don't know why I do the things that I do. It's nuts! You don't know how hard I got it, Dee
- Frank: This is some sweet smut! I'm all boned up over here!
- Charlie: In case you have to pee pee, I got this for ya.
- Dee: No wonder it reeks in here Charlie, you have open cans of pee everywhere!!!
- Charlie: Eat one of these, you're gonna wanna huff a little glue and drink some beer...
- Dee: This is cat food, Charlie...
- Charlie: I have fifty cats howling outside my window because I have ten thousand rats running around my building!
- Dee: Stop yelling, you're spitting cat food at me...
- Charlie: I'm not an idiot, there's a reason to do the things that I do...
- Frank: (while peeing into a tin can) Ocupado...
- Charlie: Wake up! Let's go... Time to start the day, time to get up!!!
- Dee: Howdy howdy howdy... How's everybody doing tonight? So you guys, whats the deal with those hands-free headsets that everybody's wearing in their ears? (retch) It's like hey everybody look at me, I'm one part robot and three parts asshole (retch).
- Audience Member: Jesus, Christ!!!
- Dee: I mean am I right or am I (retch) screw it....
|Season 4 Episodes|
| 1. "Mac and Dennis: Manhunters"|
2. "The Gang Solves the Gas Crisis"
3. "America's Next Top Paddy's Billboard Model Contest"
4. "Mac's Banging the Waitress"
5. "Mac and Charlie Die (Part 1)"
6. "Mac and Charlie Die (Part 2)"
7. "Who Pooped the Bed?"
| 8. "Paddy's Pub: The Worst Bar in Philadelphia"|
9. "Dennis Reynolds: An Erotic Life"
10. "Sweet Dee Has a Heart Attack"
11. "The Gang Cracks the Liberty Bell"
12. "The Gang Gets Extreme: Home Makeover Edition"
13. "The Nightman Cometh"