Reventón is a fun, colloquial Spanish word for a 'wild party' or a 'blowout'. It's much more energetic than your average 'fiesta'!
This word comes from the verb reventar, which literally means 'to burst' or 'to explode'. So, a reventón is a party that is bursting with energy and fun. In the song, Selena sings "Este reventón sí es para toda la bola" (This wild party is for the whole gang), inviting everyone to join the explosive dance celebration.
Get ready to move, because Selena is throwing a party and you're invited! "Techno Cumbia" is a direct command to get on the dance floor. Selena makes it very clear what the rules are from the start: "Si vienen a bailar, pues vamos a gozar / Si vienen a dormir, salgan fuera de aquí" (If you've come to dance, let's have fun / If you've come to sleep, get out of here). This isn't a song for lazy people, or as she calls them, "flojón" (lazybones). The goal is to dance without stopping until you're sweating.
What's really funny about this song is how Selena calls out specific people in the crowd who aren't dancing. She has a reason for everyone's laziness. There's María, who "no se mueve de su silla" (doesn't move from her chair) because she ate too many tortillas. Then there's José, who is just sitting because "se tomó muchas cervezas y ahora camina de lado" (he drank too many beers and now he walks sideways). It's a playful, high-energy song that's all about having a good time and leaving your excuses at the door.