1) A person or persons who is generally and repeatedly annoying, not taking the hint that you don't want him/her around. Similar to rats in the fact that they are both bothersome and extremely hard to get rid of.
2) A person who is one of several species of "Dirties" (disease carrying vermin who are obnoxiously annoying, cannot control the volume of their voice, and make you feel like you need a shower after you stand in their presence.) "Butt Rodents" usually congregate together whenever possible, and recruit every new student they can into their group, thus reproducing like rats. Most likely are enrolled in BD classes.
Person 1: Dude, Cameron will NOT shut the hell up. I tell him to go away but he doesn't get it.
Person 2: What a Butt Rodent.
Butt Rodent: Hi! I'm Kabrina! Do you have any spare batteries I could use for my walkman? *snorts*
Me: Begone! Butt Rodent!