look up any word, like spook:
 
1.
When you have a sex train going and there are not enough people to make a full circle. The person in the rear is referred to as the loose caboose.
My swinging friends invited me over for a party. My girlfriend won't go. It is throwing off the numbers for the sex train. I hope I get to be the loose caboose rocking the train.
by StyxxxCA September 27, 2009
 
2.
used to refer to a person with a loose anus. Usually happens when said person has participated in copious amounts of anal sex.
"Sally said we have to stop doing anal because she is starting to get a loose caboose."
by Anal Jim April 06, 2011
 
3.
1.) Being an anal sex fiend. 2.) girl that is an anal slut
Damn, she's a real loose caboose.
by Mab13 May 08, 2012
 
4.
Scot of the WCHL.

Yeah, one "t".... he doesnt seem to like things that come in pairs, aside from balls.
"Since Wednesday ol' Loose Caboose has set a new record for most men on board..."
by Canadian Pacific April 21, 2005