A particularly unattractive woman who is following, walking behind, or last in a group of much more attractive women.
Joey: Whoa! That chick is hot!
Ramone: Man, and so is that girl!
Joey: Damn! Check out her friend...
Ramone: Ugh... that last one though... She looks rough... what a boo caboose.
When you cheat in a game and other people in the game identify that you were cheating and threaten to ban you but before the ban you get worried so you enter the denial stage of the Kübler-Ross model where your depression needs to be mitigated through furious masturbation in order to jump to the final stage - acceptance.
Josh: "What you doin man?"
Noah: "Man I think I'm gonna get banned in {random Steam Game}"
Josh: "Why?"
Noah: "Because I was using an aimbot."
~ Later~ Noah CaptainCaboosed himself.