When one or more people of ill-repute do the nasty in a place you frequent, thereby making said place uninhabitable for fear of the resulting effect on your body, i.e. growing a third nipple, an enormous cold sore, or the worst case of anal warts you have ever seen.
My brother's girlfriend wanted him to have sex with her on my bed, but he didn't. Thankfully, now I won't have to sleep in Sexual Chernobyl.