"What is a Gimp?"

My office at work is joined with members of the CPS, there's a bit of resentment money wise (we get paid so much less than them because they're recognised civil servants while we're just police staff) but they are nice people. One of them is having a birthday on Saturday and she's been nattering non stop about it, I have no idea how old she's going to be but she's having a big party and by all acounts is looking forward to it.
Today she recieved an email from her bother in Sweden, he mentioned that as her birthday present he was sending her a gimp through the post which lead to her saying "What is a gimp?". I started giggling, one of her colleages said "oh I don't know" another said "I'll get a dictionary" I started giggling more. My colleage said to me "What have they done now? Why are you laughing?" So I explained that they don't know what a gimp is which got the reply "what is one?". So I explained to a woman my mothers age what a gimp was and then wandered over to the CPS to tell them what one was. I could feel myself turning red while I was talking to them. I'm alright talking to someone on a one to one basis but when everyone was giving me their undivided attention I could feel myself turning redder especially considering the fact that I was talking about S&M, I was just greatful that no-one asked me how I know because I have no idea how I would have answered that...I mean, how do I know what a gimp is?