A uterus that has the ability to rip through anything, including emotions and happiness. The Uterusaurus is not from the Jurassic era, nor is it a mythical creature. It lives deep within every normal Uterus waiting for the most inopportune moment to strike.
My girlfriend and I made plans to go out tonight, and I was totally going to get some, but her Uterusaurus arose from the pits of hell and cock-blocked me. I ended up having to bring her ice cream and cuddle.