When you finish peeing and put your dick back in your pants but then more pee comes out and stains your pants.
When you pee sometimes the slit fused shut and peeing is like putting your thumb on a garden hose. Some goes over there. Some goes over here. The dreaded split stream! Aim one at the toilet and clean up the other after.
It will make you make very bad decisions all for a few spasms. I knocked up my ex wife one month after our divorce was final.
Getting it stuck in a zipper
Back in puberty: Random erections, having to „lie“ to your hormone controlled guyfriends about your dicksize