you know you're an adult when you (voluntarily, with no pressure from outside influences like your mother) buy and take your own cough syrup.
I won't go into details, but my colds were never as messy when I was a child.
Four days away from turning 27.
My cough syrup says, "It's gonna suck."
You know you're an adult when you overdose on your cough syrup that you bought yourself.
Yo era tan cool.