I usually chew gum, but if I don't have any I start to chew on weird things. I like to chew on any kind of plastic- grocery bags, small plastic figurines, tape, etc.; and cardboard. I chew it until my teeth hurt!
I am a wolf therian so I guess its in my nature to chew on things. When I have a hot chocolate, you know the lids with the holes? I finish the hot chocolate and just sit there biting and chewing that.:P
Lend me your pen? You aint gona get it back, especially if you don't want it all chewed up! I hate that moment when, I put a pen in my mouth and suddenly realise I borrowed it!
I chew my nails.. which I know is a crappy habbit to have..
I like to chew paper cups, or plastic...