Every time i drink from a plastic water bottle

For about almost a year now, I've had this habit I want to get rid of. I'll drink the whole water bottle, and then stick the plastic cap in my mouth and start chewing it like gum. I want to stop but it is really satisfying. I chew it until and gets annoying and starts scraping my mouth. Then I like put it in my pocket spit it in the empty water bottle. I want to stop because some times they end up all over the house on the floor, or in the washing machine after washing clothes. Please tell me there's at least SOMEONE who's done this too. Is this habit normal?