Funny memes
Buchanan became popular in MX because of narcorridos. A corrido is basically a folky ditty that tells a story; it is called a corrido (run-through for context, I guess) because it has no chorus. A narcorrido is a corrido about narcos, or the narco lifestyle. Back in the 80's, a singer named Chalino Sanchez sang them, and usually posed holding a .45 with a bottle of Buchanan next to him, as it was apparently the whiskey of preference for the narcos. There are many narcorridos about drinking Buchanan. EL Chapo himself drank Buchanan, and it's said he preferred it over tequila.
Singing narcorridos can be dangereous, though. While there are/have been narcos who like narcorridos about them and even commissioned them, there've been a few naarcorrido singers who have been killed because a narco didn't like what the narcorrido said. Chalino himself was gunned down by narcos.