The act of getting chewing
gum from your pocket, bag, place of storage, when surrounded by a large (or if you're greedy, a varitably
small amount) of people, as so that the surrounding people do not notice you have
gum, and hence will not request gum from you, depleting your store that was meant for the next week and a half.
Guy 1: "I see you have a fair amount of
Gum there, Guy 2."
Guy 2: "Yeah, I've been Sneak-Gumming all week! Them vultures don't got nothin' on me!"
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Man: "*Chew*"
Everyone: "GOT GUM?! GIMMEGIMME."
Man: "Damnit I've never been very good at Sneak-Gumming".