1) A person who often forgets how old they are, literally
2)Someone who acts or dresses much younger or older than they are
A.I.C. for short. Developed by a girl/woman who married a man 30 years older than her and often found herself not knowing if she should act 20 or 50. She happened to suffer from both forms of A.I.C and consistently forgot her actual age, even when asked by the nurse at Red Cross.
Person 1 "How old are you?"
Person with Age Identity Crisis. "uuuuhhh....????"
Did you see that 50 year old guy with an Ed Hardy T-shirt? He must suffer form A.I.C.