A rusty tool is a person of the tool
variety that has obviously been a tool for a very long time. This is different than a tool that is very new to the tool genre of faggotry. A rusty tool has been a total douchebag for years, and is on the fast track to nowhere. Well, nowhere except for even more tool-like qualities. They don't age gracefully, kids. Don't try to be a tool for fun, not even for halloween.
Guy #1: Dude that guy is such a faggotron.
Guy#2: Nah, dude, he's a tool, he's wearing Ed Hardy.
Guy #1: Psh, dude, he's a fucking rusty tool. Look how much hair gel build-up he's got going on. Only a tool of great age could have that much funk.
Also, a good example of a rusty tool is any guy off of the popular MTV show, Jersey Shore.