DALLAS — On the January day that 10k.Caash released his latest mixtape, “Planet Swajjur,” he skipped throwing a big party and instead holed up at Legacy Music Group, a recording studio in Dallas’s Deep Ellum neighborhood.

His hair, styled in the mullet-adjacent local style known as the shag, was two tones of green — aquarium-chemical aqua at the top, nuclear neon at the tail — and he wore a Kanye West “Jesus Is King” sweatshirt.

In between snacking on Sour Patch Kids and Fritos Flavor Twists, he repeatedly headed into the recording booth and asked his small circle of producers to run through an increasingly odd collection of plinks and bloops. When he heard one he liked, 10k.Caash, 18, began spitting out loose splurts of words — “Pixie sticks!” “Move your muscles!” “Everything geeked up, I’m saying Urkel!” He hurled words against the beat, rapping as if he was learning to rap without knowing that rap music already existed.

After one particularly squelchy number, his friend and mentor, the rapper G.U.N., shouted, “This beat making me want to slam my head into the wall. It’s a 10k beat for sure!”