A character from a game found on cell phones.
Also can be a pet name for a penis
"Get your earth worm jim out and dig me a tunnel!"
Someone who appears to have muscle under their clothing, but in fact, they don't.
Tim: Look at John, is it me or has he been working out?
Mario: Nah. He's a Earth Worm Jim. Take off that sweater and he'll look like a run away chiwawa.