Take, for example, this week's episode:
It was meta-textual week on the show. We open with Ted, Marshall, and Barney in a coffee shop, where Barney notes that hanging out there just isn't as much fun as hanging out at a bar. (I originally typed "bra" there instead of "bar" and realized that Barney would probably find it more fun to hang out there too. Ah, these Freudian slips...) The barista writes the names of the customers on the rims of their cups as the drinks are being prepared, but Barney's name has been mangled to "Swarley". Ted finds this hysterical and connives with his friends to call Barney "Swarley" at every opportunity, including having Swarley paged in their regular bar hangout, tacking a sign to Barney's back saying "Call me Swarley", and just generally making his life miserable with all this. Barney, being Barney, probably deserves it.
And then we got to the tag. Barney walked into the bar by himself and every patron in the bar greets him with a chorus of "Hi, Swarley!" The bartender then flips the switch on a boom box which begins loudly playing the theme from Cheers, "Where Everybody Knows Your Name".
And then, as Barney turns on his heel to walk out the door, the closing credits for the writers and directors come up on the screen. In the Cheers font and colors.
I nearly hurt myself laughing.
These people are insane.
And if you like situation comedies, you should think about watching this show.