After 5th grade, I thought 11th grade, Junior Year, was the point of being old.
Needless to say, I didn't anticpate the whole "I'd only be 16 Junior Year in a state where you have to be 17 to drive" thing. But I still thought it would be cool. And I guess I was kinda right. I remember my Junior Year of High School as one of my favorites.
However, when I was in 11th grade, I came up with a theory that stemmed mostly from the drudgery of waiting for my 17th birthday to roll around (which would be in September of my Senior Year): that it was going to take so long for my 17th birthday to happen that by the time it was done, I'd be 18 and have missed it. Therefore, since I will be missing an entire year of my life, how was I to know how long a year was for me? Clearly, time dimensions as we know them do not apply to a person who takes 2 years to get to their 17th birthday only to turn 18. So I figured I was as old as I wanted to be. At which point, I decided I was twelve.
A few years later, I was visiting my friends in Morristown during winter break in college. I was standing in front of the AMC in the Headquarters Plaza Mall waiting for someone to finish their shift, gazing blankly at nothing. A trio of young teenagers approch me, break my stare and ask me how old I am. Without thinking, I said "nineteen." They smiled and nodded, and suddenly the clouds clear and I realize that that was incorrect. "No!" I interrupted myself, "I am twenty-one." The children looked startled, looked at me like I was nuts, and stepped backwards away from me. Maybe it was my year progression discrepancy in effect, but I later assumed that the kids wanted me to buy R-Rated movie tickets for them, and either age I told them I was was old enough to do so. I'm not sure why they didn't want my help anymore.