When someone has little to no teeth and only their gums are showing
Hey gumgum, we all know you got no teeth in your mouth.
by sparkyjo December 16, 2014
Gumgum means that if you are dumbdumb, then you MUST have the gumgum

From the movie:

A Night at the Museum with main actor Ben Stiller and statute of Teddy Roosevelt

In the movie: The Statute of Teddy Roosevelt asks Larry Daley (the dumbdumb) for some gum gum.

Obviously, dumbdumb means mentally retarded, slow or just plain stupid. So if you fit this discription, you might want to stop chewing gum to hide your true identity.
Hey dumbdumb, you got any gumgum?
by JUbie & Kito December 7, 2007
word for girl who doesnt like "babe" asians like to be called gumgum by hot white guys. Preferably Romanian.
Dont call me babe, its cliche.
OK, ill call you gumgum.
by jackiejackbear July 15, 2010
A religion in which we almost always need to chew gum. We chew it at work, school, at the park, and wherever else we please. We can also wear hoods in buildings no matter who says we can’t. Every Wednesday we go to church and chew gum, sing songs, and have baking contests. There are about 20,000 people in this religion but more are still joining monthly.
Teacher: Please spit out your gum.
Student: Sorry I can’t it’s against my religion, GumGum Church.
by GumGum church October 9, 2019