What stupid lie to you tell kids to amuse yourself?

Instinctively, kids seem to think I'm somewhere between the age of 18 and 22 (although I did get a "I'm not being funny Miss, but you look about 14" recently), when I'm nearly 30.

Because they think I'm particularly young, they'll ask me how old I am pretty regularly. I've started telling them that I'm 42. When they act shocked I tell them this is what happens when you don't smoke/vape and use SPF.

What is currently helping with the lie is I've currently got a hip injury from absolutely nothing.