What do you do when your daughter tells on you?

My little sister is five and I keep her a lot for my mom since there's a big age gap between us. She does the same exact thing so when she does something embarring I yell it aloud as well. For instance if were in the mall and she picks a wedgie I yell EWWW jayce's picking her wedgie. Trust me it works. Its kind of embarring at first to yell it aloud but it fixes the problem.