Bultero is sorta like a wannabe or a try hard. For instance, someone who lives in a shack, and carries an i-Phone is a bultero, because he's trying to portray that he's richer than he is. Or people who will go to a concert of music they don't know, or don't like just to be part of the crowd would be a "bultero". Bulto means mulk, so they are bulkers. hehe. Or a guy who drives a car that is worth more than his house could be considered a bultero.
Cara de Semilla - Seed face, My gf calls me this to say I'm an idiot, not sure if it's her thing, or used elsewhere.
Some other things used amongs the youth.
Charly - used to describe something corny, or lame. Esa pelicula esta bien charly.
A lo focker - not an insult but a way to describe someone doing something whithout shame or scruples. "Comio todo mi comida, asi a lo focker". I know it sounds like the F word, derrived from the f word, but generally considered mild in its use.