What was going on with Dennis in 'Charlie Work' (S10E04)?

During the It's Always Sunny in Philadelphia episode "Charlie Work" (S10E04) Charlie has Dennis play the barkeeper during the health inspection. But all he ever gets out is a quite nervous McConaughey-style "Alright, alright, alright". He seems to be in a complete tizzy and at the end when he calls back to the health inspector all he gets together after an awkward pause is another "Alright alright, alright", all while sweating like hell.

So what on earth was wrong with him? Was he just overwhelmed by the "stage fright" of playing the barkeeper? Though, I'd not say this is a particularly difficult task for Dennis, especially since, like anyone else except Charlie, he didn't give a damn about the health inspection anyway. Did I miss anything else or was he really just totally nervous about his barkeeper role for whatever reason?

Best Answer

Fun fact: This episode was an homage to True Detective, strange as it may sound.

Background: In early 2014, HBO released the first season of True Detective, which quickly earned rave reviews and plenty of fanfare. One of the more impressive feats by that first season's director, Cary Fukunaga, was an uninterrupted, action-filled 6-minute-long tracking shot in the end of episode 4 (you can see it here). Inspired by this frantic single take, the IASIF gang decided to pay it homage. From a Yahoo article about Charlie Work:

The FXX sitcom, inspired by a long, unedited shot in the HBO series last year, fashioned its own for Wednesday's episode (10 p.m. EST).

"True Detective" followed Matthew McConaughey in and out of frenzied danger for six seamless minutes. The FXX sitcom spends an uninterrupted seven-plus minutes on a scene that's equally manic but minus the gunplay: It involves a desperate bid to save Paddy's pub from flunking a health inspection.

Glenn Howerton, who plays Dennis and is an executive producer of the comedy about a group of loser pals, said they were "pretty inspired" by the bravado of "True Detective" and found an episode that's served by the approach.

So in Charlie Work (which aired almost exactly a year after the TD episode it was inspired by), Dennis's impression is a nod at McConaughey's role on TD, and his gradual disintegration is funny in both the narrative and in a meta way: Dennis is clueless about being a bartender (a job usually manned by Dee), especially a good-natured one, and can only think of a single schtick - but this is also the extent of Glenn's McConaughey impression, and he doesn't know what else to do. [It's also worth noting that McConaughey's character on TD is often in shambles due to the effects of narcotic abuse and transforms from a young go-getter to an old drunk. Sunny might be deeper than we thought. ;)]