Once I fired an over-and-under 12 gauge shotgun and both barrels fired at once. Bruised my shoulder pretty bad.
The funny thing is I'm almost notorious amongst the gun owners who know me (even my dad) as being able to shrug off some mean recoil.
For example two instances:
1. I was at a friend's house and he had guns to shoot. The "big" gun of theirs was a .444 Marlin 336 lever action. I shoulder it and expect it to hurt, and fire it. I then turn to my friend's dad and ask, "That's it?" He laughed.
2. After firing a 10 Gauge twice, my dad askes, "Had enough?" I replied, "Got anymore?" haha. He had buckshot left, which kicks more. Shot four of those as well, no problem.
My love of guns overwhelms my discomfort of pain.