There are lots of things that suck about being a "grown up" (such as April 15 Tax Day, bills, responsibilities, etc.). But there are lots of cool things too.
One thing cool about being a grown up:
You can eat whatever you want whenever you want.
Chocolate milkshake for breakfast. Fine. Tuna sashimi and wasabi at 10pm, fine. scrambled eggs at 2:00 in the afternoon, fine.
I like that.