Kevin the Teenager to levels where he got his own movie.
Seinfeld Is Unfunny: Wayne and Waynetta Slob were supposed to be over-the-top caricatures of every negative stereotype of poor council-estate dwellers but since the word 'chav' entered the national consciousness and everyone started doing it, they seem unoriginal and not particularly funny.
Sequel Displacement: In a sense. Kevin The Teenager is really a sequel to the "Little Brother" series of sketches but, while anybody in the UK who watched comedy shows in the nineties will be able to quote Kevin and even imitate his mannerisms, very few of them will know that he evolved from the Little Brother character. (Unless, of course, they saw the sketch where the transformation occurred: at the exact moment he turned 13.)