This thread amuses me!
I was a major gum sticker into college. I very easily could've wrapped the gum into a piece of paper or tucked it between my teeth and cheeks but I didn't. I had no good reason for this habit, because I really didn't think about it. I know I liked to add to the gum that was already under desks and make the gum lobs even bigger. It was my form of vandalism, and yeah it was gross.
Also, I'm not particular grossed out when I touch gum stuck to chairs and whatnot.