A) ultimately, what really matters is, fundamentally, at all

Example> Then I looked more closely and by gum , found a rainbow lurking in the mist ahead.

Example> But what he was really good at was machines. By gum, he could make them go! He loved anything mechanical, did Walter.

Example> If he were elected , by gum , things would be different

B) in general

Example> When we produce reporters who purport to be devoted to balance and impartiality , by gum , they deliver just that.

Other usages:
"By love, by gum"
"Eat bone by gum"

A chewy, sticky wad of flavored sugar (or sorbitol or xylitol if it's sugar-free, smarty-pants) that may come as a ball, a stick, a cube, a 6-foot strip in a pink plastic dispenser, etc. Typically flavored as either classic bubblegum, a fruit (juicy fruit, strawberry, watermelon, orange, kiwi, pineapple, dragonfruit, etc.), or some kind of mint (peppermint, spearmint, wintergreen, winterfresh, sweetmint, smooth mint, polar ice, fresh mint; the list goes on. What's the difference? Don't ask me.). Common uses include sticking it under desks, putting it in people's hair, playing with it as slime, using it as a currency/bribe, breath freshener, etc.

An imaginary aliment suffered occasional by office employees. Actually an acronym that stands for "gotta use my sick-time." Used to describe someone who calls in sick without actually being sick simply to use up sick time before it expires.

High School Currency

something you chew on when your bored in class

a bachelor's toothbrush.

A delicious rubber like candy that people chew when they are bored or are hungry for sugar.
Bubblegum is gum you chew and can blow bubbles out of.
Chewing gum can only be chewed, most people chew chewing gum for fresh breath.
Gum has many different flavors.

Most common for bubblegum: Strawberry
Most common for chewing gum: Peppermint