What to do when you get kicked in the testicles? - Lay down and rest - Put an ice pack on the area - Elevate the area with a rolled-up towel underneath the scrot.
You'll definitely feel pain if your testicles are struck or kicked, and you might also nausea and vomiting; or if you develop a fever, get to a doctor immediately.
Now, realise that they always say “Get kicked in the balls”, and not “Get kicked on your penis/dick”? If one's penis actually got kicked the pain would be a lot more.