I created this problem myself, but I did have inspiration.
Today is a special day, I'm moving out of my parent's house. My father comes to me and says "Wow, you're half my age. On the day we moved into this house, I was four times your age, and your brother Bob was 3 years old." To which I reply "Good times. I remember the day when I almost burned the house down, you were three times my age, and I was twice as old as Bob."
My father then asks "How old is Bob anyway?" We think about it a minute and then my father's eyes bulge out "Bob can't be 27! I am not losing my mind, am I?"
"No", I reply, "Of course Bob is younger than 27. Actually, he is the youngest he can be given what we've already said". How old is Bob?
A useless hint:
As by convention, a person is said to be X years old, if he has lived at least X years, but has not yet lived X+1 years. A person's age is an integer. If I say someone is three times my age, and my age is X, then their age is 3X.