If you search for the hashtag #TacoTuesday on Twitter, you'll get literally thousands of results, everything from pictures of strangers' dinner plates to dogs in taco costumes, along with tweets from Canadian sommeliers and Mexican restaurants in Jamaica. And if history really does repeat itself, every single one of those taco-loving hashtaggers better brace themselves, because Taco John's is probably typing up a cease-and-desist letter right now.

Earlier this week, the Houston Chronicle investigated why the phrase "Taco Tuesday" isn't used more frequently in Texas restaurants and discovered that it's because, well, it can't be. Taco John's, a Cheyenne, Wyoming-based fast food chain, has owned the trademark for Taco Tuesday since 1989, and it is serious about protecting it. (Obviously, because nothing says 'authentic midweek Mexican dining' quite like Wyoming).

Taco John's does not hesitate to have its attorneys get in touch with any restaurant that uses the alliterative phrase. In 2010, it went after the Iguana Grill in Oklahoma City for using "Taco Tuesday" to promote its weekly $1 taco night. "We had considered trying to fight them or work an agreement with them since they're not in Oklahoma," executive chef Ryan Parrott told The Oklahoman. "But we decided to stop using it and change the name. But we won't stop the event."

In 2014, Taco John's challenged The Old Fashioned in Madison, Wisconsin, which had been running Taco Tuesday promotions for nine years. "At first we were kind of — not angry, just perplexed," said Old Fashioned manager Jennifer DeBolt told The Cap Times. The restaurant then decided to hold a contest to rename its taco night, and received some top-shelf suggestions like "Trademark Tyrant Taco Day" and "The Tuesday Special That Shall Not Be Named." It eventually went with "Ole Tuesday."

Billie Jo Waara, the chief marketing officer at Taco John's, told Priceonomics that "Taco Tuesday" was first used in the early 1980s by David Olsen, a Taco John's manager in Minnesota. Business picked up thanks to the cleverly named specials, so the chain started using it in advertising jingles. In 1989, Taco John's filed a trademark application with the U.S. government and was rewarded with Trademark No. 1,572,589. By the website's count, the chain has sent out "hundreds" of cease-and-desist letters to other restaurants since then.

Weirdly enough, Taco John's only owns the trademark in 49 of the 50 states. In 1979, Greg Gregory, a second generation New Jersey restaurateur scored a trademark for "Taco Tuesday." Since Gregory beat Olsen to it, Gregory's Restaurant and Bar in Somerville is the only Jersey restaurant that can use the phrase—and it still does. Its Taco Tuesday special is currently two tacos for $1.75.