On the rare occasion that someone takes it upon themselves to make a racket in the theatre, I’ll usually just go the “Shhh” and “Can you please stop talking?” route.
However, one time some doofus was taking great pleasure in giving a running commentary to keep his girlfriend amused. After three or four "Please be quiet"s, the talking and giggling still didn’t stop, so I got out of my seat (I was near the aisle, luckily, so I didn’t have to step on anyone’s toes) and walked over to them, two rows back, and said in a very stern voice “If you don’t stop talking right now, I’m going to ask the management to throw you out.” A few people around me looked at me and nodded approvingly. The guy couldn’t have been more than 16 or so, and he looked a little scared, but with a girl in your presence, guys become a lot braver/stupider than normal. He nodded at me so I sat back down. About a minute later, I felt a few gummy candies being bounced off the back of my head. They also managed to hit the guy next to me, who was rightly indignant. I looked at him and motioned to the drink in his arm rest.
“Can I have that?”
He agreed. I turned my head to the side and waited until the guy bent down to pick something off the floor before I let it loose. He sits up straight, and BAM!, it lands right in his lap. Pop sloshing, guy and girlfriend yelping and swearing alternately, the beautiful sound of ice cubes tinkling on the floor, and the laughter of fellow patrons. Too bad it was only Sprite, because Orange Crush would have decorated his white shirt very nicely. They got up and walked out, mumbling and swearing the whole time. A few minutes later, some theatre jockies came in and stood around for a bit in the dark, looking properly officious, until they decided they had done their job and left. No court in the world would have convicted me anyway.