Marble Mouth 

A person who talks like they have a mouth full of marbles

Wonder what Marble Mouth is going to try and say?

Marble Mouth by unstable bob June 30, 2017

Marble mouth 

"Marble Mouth" is a slang term used to signify people who possess a slight speech impediment. It's hard to describe, but it certainly has nothing to do with location or cultural background like one definition ridiculously stated. It's not that they stutter - they don't necessary. But it's obvious that speaking is not their strong suit and they sound as if they have a mouth full of marbles. Marble mouths, more than anything, are highly annoying because you just want them to spit the words out already.

Eli Manning. A perfect example of a marble mouth.

"Just waanted to go dowanfield and duhduh get the win."

Marble mouth by Stormvessel July 1, 2015

Get the marbles out of your mouth 

Urging someone to speak, sing, or write so that they can be heard or understood more clearly

You need to get the marbles out of your mouth — I could barely hear that last verse.

Get the marbles out of your mouth by Lazarus Online December 10, 2022