The CBS comedy kicked off its nine-season run on Sept. 19, 2005. In looking back at her time on the show, Alyson Hannigan remembered that "we used to have amazing pun runs on the show. I don't know why. I think it started with somebody mentioning Cat Fancy, the magazine Cat Fancy. I think it was a guest star and I don't know why that started a pun-off, but [there were] years of puns. Oh my goodness, we would laugh so hard at the puns that would happen... We got really good at punning." ALSO: Why each HIMYM season is the best.