Well you did say you were told chewing gum was a filthy habit.
And what about bubble gum? I spent many a happy hour as a child seeing how big I could make the bubble before it popped. You got a better result with two packets of gum. Other children would try to clap their hand over the bubble so you got a face full of sticky goo!
Incidentally, I was surprised to notice from various Scandanavian thriller progs that it seems to be alright to chew gum over there. Police Inspectors do it whilst behaving in an authoritative manner.
Wicked Little Letters? (funny film of a long-forgotten case)