37 weeks pregnant with my first child...what does a contraction feel like (other than a menstrual cramp)??

I am 37 weeks pregnant with my first child, and everyone keeps asking me if I've felt any contractions. The thing is.....I have no earthly idea what a contraction feels like. Everything I read basically says a tightening of the uterus.....some women say they feel like menstrual cramps. Some say they are painful, while others say they're not. Sometimes it feels like I am being kicked in the cervix, but that doesn't hurt - somewhat uncomfortable, but not painful. I know every woman is different, as is each pregnancy, but can someone please provide me with a better description of a contraction????