10 Hilarious TV Running Gags That Lasted An Insanely Long Time

10. The Slap Bet - How I Met Your Mother

How I Met Your Mother had an absolutely insane number of running gags throughout the series, including the military salute, jokes about Canada, Barney's job, and Robin Sparkles, but the most prominent one was there for practically the entire damn show.

In the episode Slap Bet from Season 2, Barney loses a "slap bet" against Marshall, a form of betting where the winner can slap the loser once across the face. However, due to a complication, this is extended into five slaps that Marshall can dole out at any time he wishes from then until the end of time. For the next few seasons, Barney always has the threat of a slap hanging over him, a really clever idea which makes it so the writers can surprise viewers with one in any given episode. The most out of nowhere slap happens at the end of Barney's play in Season 2, although usually Marshall makes it into more of a spectacle with Slapsgiving.

The writers loved this gag so much, they actually had to modify the bet to give Marshall more slaps. That way, they could keep the joke going for the full series. It ended up lasting from Season 2 Episode 9 all the way to Season 9 Episode 22, where Marshall uses the final slap at Barney's wedding. Now that's dedication to a bit.