When your family has to hide decks from you so you don't use them and loose cards. (Found one in the kitchen drawer that said with marker written across it "Full deck. Adam, do NOT touch!)
-You put anything resembling the size or shape of a playing card in tenki without even noticing.
-You can perform a Monte routine with sugar packets.
-People wont play cards with you even though you suck at poker.
-If you cut imaginary decks while you are sleeping. Seriously, ask my ex. She hated it when, even while I was sleeping, my hands were performing charliers on decks of cards that weren't there. It would wake her up and she couldnt go back to sleep...whatever, I slept great.
-When you watch movies, you don't eat popcorn, you perform charliers. The only way to watch a movie.
-If you are playing with a deck as you read this post.
Alright, I think thats it for now. I just got off a 12 hour shift so I think I am going to lie down. I will post more if they pop in my mind and I HAVE to share them with you. Great thread OP, gave me a good needed laugh.