What do the stars underneath my name on my profile mean?
Member rating yo.
So its like owned by Tbell or something?
Taco smell is owned by Yum! food, and Mountain Dew by PepsiCo. Taco Bell has exclusive rights to Baja Blast though. Probably some sort of business deal that benefits both companies 
So the higher the better? Because it just went up to 4 stars from 3 stars so does that mean a mod upgraded me or something? Or how does it go up or down?
And that kind of sucks i guess. Because I would love to get two liters of it.
Members vote you from one to five stars. The amount of stars you have is an aggregate level from all the votes. One being the worst, Five being the best.