I hate to admit it but I started only when i was in university. I often studied with my boyfriend (now hubby) He often forgot his pens and had to borrow mine. He was a big big big pen chewer and soon all my pens, rulers in my pen case were chewed. Even his electronic pda stylus had to be replaced as he chewed on it so much! At first I didn't like it because all my pens looked deformed but one day I tried chewing on them more to see what the kick was and got hooked! I know it sounds silly but it was actually quite therapeutic when you are trying to read a hard chapter or think of an answer. It is also quite gross that we both chew each other pens and probably ingested each other's spit.

not much different then kissing though!
So these days, all our pens in the house have both our teethmarks! (We can recognize who's teethmarks it is too!) It is also ironic that my 9 year old is the one nagging us to stop the pen chewing!