Steelados is similar to n00b. Meaning of course one who has game experience and should have gotten better, yet hasn't, or one who has no experience. In either case what separates them from a newbie is that they are arrogant, believing they are better then any experienced player. Ever. Its origins are suspected to be on a role playing chatroom.
Did you see that guy who just got fragged? He was such a steelados.