“This is what I feel comfortable in,” That Mexican OT says. “When I first started rapping I was putting J’s on, fitteds, trying to look like a rapper. It wasn’t working. As soon as I just started being me? Brrrwhoosh.” He mimics the sound that rockets make when they blast off from Johnson Space Center, raising his open palm toward the cosmos.

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The “OT” in his name is short for “outta Texas,” but that “T” might soon stand for “this world,” based on the success of “Johnny Dang,” a viral summer hit named after the famous Houston jeweler to the rap stars. Over a slow-broiled beat, That Mexican OT supplies a whirlwind of Texas tough talk, rolling his R’s as if electrocuting every syllable in which they appear, judiciously channeling the styles of his Lonestar forerunners — Bun B’s dexterity, Devin the Dude’s playfulness — into a flow of his own. And if that wasn’t already Texas enough, the song’s closing verse belongs to Paul Wall, sounding remarkably agile in legend mode, delivering what must be his greatest contribution to a three-man posse cut since 2004′s God-tier Houston anthem “Still Tippin’.”

The rest of OT’s new album, “Lonestar Luchador,” feels remarkable for its craftsmanship and its sense of humor — a levity that feels rare beneath the bruise-colored cloud that’s been floating over rap music for so many years. According to OT, the buoyancy in his music — the wit, the vitality, the prioritization of fun — is entirely purposeful. “I mean, who gives a f— about your problems?” the 24-year-old asks, as if laughing at himself in the mirror. That said, we would be foolish to assume he lacks his share. “At a young age, I just became very broken,” he says. “I hated everything about myself. My name. My ethnicity. The way I looked. My hair. Everything. I despised everything about myself. But now it’s my career to be myself.”

As soon as he was old enough to talk, he was old enough to rhyme. That’s what his family told him, anyway. He says his sleepy childhood hometown of Bay City, Texas — more than an hour southwest of Houston — always felt half-deserted, yet filled with music. OT’s father, Carlos Moreno, says he remembers driving around Bay City, quizzing his kid with the car stereo, teaching him the difference between John Coltrane, Geto Boys, Corrosion of Conformity and Aerosmith whenever they weren’t trawling for Houston rap songs on 97.9 the Box. Back at home, OT remembers becoming enamored with New York hip-hop through the video game “Def Jam: Fight For NY,” a music-biz combat game that tossed the likes of Busta Rhymes, Ghostface Killah, Redman — and, for some reason, Henry Rollins — into assorted punch-and-kick scenarios.

So from the very beginning, OT learned to associate rap with play. “I could point out different things in a room and say, ‘Try to freestyle about these things,’ ” Moreno says. “And he’d close his eyes for a second, and say, ‘Okay, I’m ready,’ and then he’d just go.” (Brrrwhoosh.)

“My mother was jamming rap, too,” OT says. “I think she liked those Black boys, and she liked 50 Cent, so she would buy 50 Cent posters for me, but I think they were for her, you know?” Once his laughter evaporates, OT’s voice gets quieter, as if he’s now talking only to himself. “I miss my mama sometimes. When I was a kid, I used to fantasize about being older, about being able to hold her, and put my chin on the top of her head. I always wanted to hold her that way. I haven’t thought of that in forever.”

OT’s mother died in a car accident when he was 8 years old, and he remembers his sense of self spinning out of control. He became introverted, isolated, quick-tempered. “I was lonely,” he says, “and I was angry.” He relocated to Austin with his dad around middle school, started getting into drugs, kept getting into trouble, but never stopped rapping, until the temperature inside his head eventually cooled down. He says that his current happiness is something he gradually “walked into,” and that he didn’t really figure out that he was funny until “like, last year.”

“People always ask me in interviews, ‘What does success look like to you?’ I’m like, b—-, I just want to be happy! I’ve been so angry all my life, to this point where it’s almost natural to be mad, natural to have that bad spirit on me. I’m tired of that,” OT says. “I have good money coming in now. My music’s being known. I’m more than comfortable. So I can finally sit here and be me.”

Being himself means working with a clear mind, even when he’s rhyming about his off-the-clock pharmacological misadventures. (During “Groovin (Remix)” from “Lonestar Luchador,” he raps, “I said them Xannys, they make me do things I don’t wanna do/Puffing on the poison, now I’m moving like I’m chopped and screwed.”) “But I don’t even get onstage if I’m not sober,” OT says. “That’s why my music sounds so great. Because I put every blood cell I got into it. I care about it. I cherish it. It’s a blessing. I would never want to disrespect it. That’s why I treat it so delicate.”

You can hear that level of care in his verses, right down to the consonants — a surprising number of which he knows how to roll on his tongue. Aside from the obvious R’s, what other letters are in his arsenal? OT closes his eyes and starts trilling under his breath. “Okay, so, L’s, T’s … D’s …” And then he gives up. “Really, what it is, I just let my words slang into each other. I talk very slurrish.” Which means all those rolled letters are smearing and accentuating his words simultaneously — low-key virtuoso stuff, big fun to imitate, mostly impossible to replicate.

Halfway through Tuesday night’s sold-out show at Jammin Java in Vienna, everyone is rapping along anyway, laughing when they can’t keep up, cheering when they know better than to try, and occasionally tossing their belongings onstage in hopes that OT will toss them back autographed: felt cowboy hats of various shades, at least one bra, a wrestler’s golden championship belt. Between songs, the crowd chants his name, unprompted: O-T! O-T! O-T! “I didn’t know!” he shouts back, basking in his own disbelief, and now the smile looks even wider than the hat.