the beating refers to the overusing of the " dead horse ". Said horse is a metaphor for a joke, and the fact that it's no longer living implies that it's no longer funny

person1:hey...is that a dead horse person2:uhhh.....yyy..yes i believe it is...why do you ask?person1:oh no reason...say...you wouldn't wanna beat that dead horse would you?person2:i thought you'd never askpersons1+2 proceed in beating the dead horse five minutes later, cop enterscop:hey are you beating that dead horse?persons1+2:yes...cop:...well...care if i join you?persons1+2:not at allcop starts shooting horse whilst the tho persons continue to beat it with sticks, fade to black, THE MORE YOU KNOW enters along with someone from Friends talkin' about some stupid crap.THE END...But is that really the end?...Yes, yes it is...Or is it?