The makers of Heisler don't mind, though; you can bash their beer over someone's head for all they care. They make breakaway bottles of Heisler for that very reason. "That's the thing," Rummel says. "You can do anything with Heisler, and that's part of the joy of it."
You can also put anything in a bottle of Heisler, but when Studio Graphics sells one, it's filled with non-alcoholic beer. "You can pour it in a glass, pop the cap off of it, and it's going to look just like beer on camera," Rummel says. While shooting, actors often prefer to fill their bottles or cans with soda or sparkling water since the taste of non-alcoholic beer can get old fast. For a recent shoot for It's Always Sunny In Philadelphia, Rummel says, the cast, which has spent a big chunk of its past 12 seasons drinking onscreen, "put the labels on regular cans of water so they could do take after take after take without getting sick."