In the 1960 classic The Magnificent Seven, Eli Wallach played the bad guy, a Mexican bandit named Calavera. The role required him to wear gold caps on two of his front teeth. During the first week of filming he had quite a bit of trouble with the caps falling out. It turned out they were becoming detached because the actors drank real tequila on the set which melted the glue that held the caps on his teeth. He went back to the dentist who gave him some special “anti-tequila cement” and had no further problems after that.