I'm sure I'm not alone in reminding my children of their actual age versus the age they are acting. I actually try not to do that because I think in some ways it minimizes the feelings a kid might have. (For example, if you are 6 and pouting in disappointment because didn't get to play a game before bedtime, being told to act your age isn't very helpful because quite frankly, pouting is a 6 year old behavior. It's better to give them some ideas of appropriate behavior for dealing with disappointment.) That said, I do say it from time to time.
Apparently more than I think because last week at Grandma's, Zeke started throwing a fit and Kenson quickly piped up, "Zeke, how old are you?" Conleigh, who was sitting on the couch next to the two of them, immediately jumped in. "Yeah, Zeke you are acting like a one year old!"