I've always kept floss in my car just in case, so I can clean my teeth after eating at a restaurant. I also keep gum in my car. Rather than using the traditional floss that you may picture in your mind, I bought some little gadgets that have the floss pre-threaded on a little plastic horseshoe with a handle. That way you can one-handedly floss.... even while driving down the road. Always one to multi-task, I can drive and floss.... but I find --not chew gum.
I had popped a square of Trident sugarless gum in my mouth and chewed all the sweetness out of it. Then I absent-mindedly reached for my floss stick and started picking at my teeth. Well, whaddya know!? The floss got stuck in the gum. Now I have this plastic stick with a wad of gum on the end and no trash bag in sight.
The Kleenex box saved the day, and I drove merrily on my way. So I learned that I can't floss and chew gum at the same time.