My Dad taught me this after I took a penalty kick square to the groin during a soccer game. It is goddamn magic and I am horrified more guys don’t know about it.
The pain of a ball shot is caused by everything down there contracting very quickly and very violently in what I assume is a misguided attempt to make it a smaller target. You can counteract this by lying on the ground and having a friend lift you by the belt or waistband. This will stretch the muscles of the area and reverse the painful cramping. If you are by yourself or are not comfortable with this, lie down and lift your groin upwards as though you were going to assume the crabwalking position.
I have seen this turn laboured breathing and teary eyes into walking around normally in a minute flat. SPREAD THE WORD.
EDIT: Just to clarify, lie on your back, facing upwards.
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