The mayor of Oklahoma City is celebrating the completion of a personal mission: ridding the city’s airport of cow-tipping T-shirts.

Mayor David Holt said on his Twitter account that after months of trying to end sales of shirts reading “Nothing Tips Like A Cow” at Will Rogers World Airport, the clothing has sold out and won’t be restocked.

Airport spokesman Josh Ryan said that the shirts with the shape of the state and a cow lying on its back were “pretty popular” for over 10 years, but that “the joke has run its course.”

Cow-tipping is a largely debunked legend in which rural youths sneak into a pasture at night and push over a cow that is standing, but asleep. Debunkers point out the practice is unlikely to succeed, largely because cows don’t sleep standing up. However, Oklahoma cowboys can still reportedly sleep in the saddle.