-You wake up thinking you're damp from sweating during the night, but then realize you pissed yourself...
-You completely black out, then come back to reality at 3am in your hotel lobby in your boxers
-You crawl into a dryer and refuse to come out
-You start biting twist-off caps
-You tell people at the party you live there when you have no idea where you are in the first place
and my all time best: You know you're drunk when you find a loose sign post with a "SPEED BUMP" sign attached to it, yank it out of the ground, and go running down the main street of your campus at 4 in the morning with it. Campus police stops you with it, and you tell them its "for a school project"