I can't recall the movie name, but the scene had the good guy hanging from the ceiling as the bad guy passes underneath. As the baddie passes underneath, the good guy swings down, ending upside down while hanging from his knees. Then he shoots the bad guy as he turns around.
So a friend and I decided to try this with a 20ga Stevens single. We didn't have a pipe to hang upside down from, but we did have two picnic tables stacked. I hung over the end, he sat on my shins, and I touched off that Stevens while hanging upside down. Hit the target too!
BUT....
A) Holding a middling heavy shotgun on target while upside down is harder than you'd think, especially since you have to turn your fore hand upside down to support the stock.
B) You aren't going to get a good shoulder weld while upside down. This means you get a rather impressive bruise on the front of your shoulder.
C) When you fire a shotgun while upside down, the recoil makes you swing backwards like a pendulum. Which means the table leg gives you a rather impressive bruise on the BACK of your shoulder.
D) You will have enough time to set the shotgun down on the piece of carpet you set below you just in case...which is fortunate, because your friend WILL be laughing so hard that he'll let you drop headfirst onto it.
I learned my lesson though...I have no plans to ever be a teenager again!