Yet another of the opposites/sarcasm family of words meaning unimportant, inconsequential or useless. Became popular in the early 90's with the gen x'rs.
Matters about .25 cent hiballs look at the line up to get in! Hey I'm about go a week without smoking! Matters! Call me when you get to a year! Oh man look at that chick she's slammin! Matters dude your so whipped you may as well cut your own nuts off.