Does your age fluctuate?

I bought a fast food lunch a few days ago, and without comment or inquiry the boy gave me the senior discount. I was a bit surprised, and said nothing. I never straightened out the error.
Have you ever lied about your age to get a discount or freebie, or lied about the age of one of your offspring so your seven year old could get into a museum or buffet for free?
Do you feel such lies are okay?
If you have ever done it, did you get caught?