Chew Adieu

The "'Disappointed Mother' Anti-Chew Pen" idea gave me this idea for a cheaper, and (in my opinion) more effective solution to the same problem.

If you're annoyed by your co-workers/classmates/comrade's pen- gnawing habit, simply spritz a foul-tasting, yet nontoxic liquid on their pen caps. This organic and naturally extracted liquid, marketed as "Chew Adieu", is packaged in small, pocket-concealable spray bottles. Soon, if applied enough times, the spray will eventually induce a Pavlovian response where, every time the colleague thinks of chewing their pen, they will get a bad taste in their mouth. This will wean them off the habit over time.