Yeah; it didn't happen often though because usually they ask my age, and I won't lie if they ask. I used to be the other way round actually. If I wanted to buy a 15/18 DVD/game, they would think I was too young, and ask for my ID. On one occasion, I didn't have it, so couldn't buy it. Both of these things were quite a while ago now, but I still sometimes get asked about whether I need an adult or child ticket.
When I started my clinical practice as a dentist at age 24, I used to talk, dress and act in a more mature manner, so people would feel I'm older. With age comes experience and patients prefer an experienced doctor. After doing good work, when they realized I'm very young in the field they used to be surprised and happy . Didn't lie directly, but pretended nevertheless