As we say in our part of the world, you're either a wanker or a liar.
Prostate cancer is actually quite serious, although not usually life threatening. As women do checks for lumps in their breats, men should be sure to check for lumps in their groin on a regular basis.
So next time your better half tells you off for spending an inordinate amount of time scratching your crotch while watching the football on the couch, drinking beer, tell her you're doing it as a health precaution.