My daughter didn't turn 18 until the August following her senior year of high school (high school typically ends in late May up to the middle of June). That was a bummer for her - that meant that at her high school graduation, most kids were over 18 already, but she was not...

I started school before 5 (long story) and was one of the youngest in my class when I graduated...which meant I needed to drink twice as much beer at grad parties just to prove myself. By late July I'd already proven myself against my fellow H.S. grads, and moved up to college grad parties. <s>