What is too old?

When do we become too old? Is it a specific number only...or...is it tied to an event?

I think we'd all agree that there comes a time when you are too old to sleep with the light on. Or we can be too old to publicly announce that we successfully used the bathroom. Or we can be too old to really want to play in the ball bath at Chuck E. Cheese. (or perhaps maybe that is more of knowledge of what is actually IN the ball bath that causes us to not go in)

But are there things that we are never too old to do? And if so, how do we determine what age that occurs? Am I at age 27 too old to be a competitive athlete? In NFL years I'd be the equivalent of a 60 year old, yet, on the PGA tour, I'd be about 5 years old.

Are we ever too old to enjoy coloring? or cartoons? or water baloon fights?

Or are you simply too old once you're 21?

Note to self: Am I too old to play games?