Loquerón is a powerful slang term that doesn't have a perfect one-word translation. It's built from the word locura, meaning "craziness", and adds the augmentative suffix -ón to make it bigger and more intense.
In the song, the singer says "traigo un loquerón", which means he's on a wild, crazy bender or party spree. It perfectly captures the feeling of being in an intense state of wild partying for days on end, which is the central theme of the track.
Tito Double P kicks off this track by painting a very specific scene. He's got his cap on sideways and his eyes are low, or "ojos tumbados," and he's rolling with his crew. When they lower the car windows, a cloud of smoke smelling like "pura flor" (pure flower) billows out. It's a party, and it's been going for a while. So long, in fact, that his girlfriend keeps calling, wanting him to come home. His response is brutally direct: he tells her to consider him lost because he's with her friend, and adds, "lo mueve mucho mejor" (she moves it much better).
The whole song is built around this idea of a "loquerón," a state of wild craziness. The chorus is a message to his absent girlfriend: "No te tengo aquí, a mi lado, pero me la paso chingón" (I don't have you here by my side, but I'm having a great time). He makes it very clear this isn't about heartbreak. He's been partying for four days straight, and as he says, "no es por amor el loquerón" (the craziness isn't because of love). It's purely about the party, the flashy Rolex, and the wild lifestyle.