Marra is a Brazilian Portuguese slang term that refers to a strong, often defiant, attitude or swagger. It implies a certain confidence or boldness, sometimes bordering on arrogance.
In the context of the song, the singer tells the person to "para de marra" (stop with the swagger/attitude) and "vem viver o momento" (come live the moment). It's an enticing word because it's a less common, more colloquial term that adds a lot of flavor to the lyrics and gives insight into informal Brazilian Portuguese.
Get ready for some direct fun with Mc Jacaré's "Motel Barato"! This song is all about seizing the moment and not overthinking things when the attraction is strong. Jacaré makes it clear from the start with lines like "Olhou forte pra mim / Sem pensar eu 'taco' dentro" [Looked hard at me / Without thinking I 'throw' myself in].
He's not claiming to be overly emotional or violent, just very much in the present. He tells his love to "para de marra / E vem viver o momento" [stop being difficult / And come live the moment]. The location doesn't matter, whether it's "No beco, ou no carro / Num motel barato" [In the alley, or in the car / In a cheap motel] – the only thing that's important is the person he's with. It's a blunt, playful take on spontaneous romance!