shtummer 

A person who is told to keep "shtum" (quiet) but continues talking shit regardless

What a shtummer that uri really is. We told him he's full of shit but he won't keep shtum

shtummer by Pale Orc April 4, 2015

Shummer 

When something is both a shame and a bummer from an unfortunate incident.

Person A: "Dude, I think I failed out of college."

Person B: "That's a shummer. What a way to go..."

Shummer by Christine Hampton September 24, 2011

Stummer

When someone is incredulous when confronted with a fact.

“Oh mate, you a full on stummer “

Stummer by Arthur Mix August 12, 2018

shummershault 

The act of doing a somersault while shumming. See shum.

I saw Jackie shummershault after Matt put his nut in the butt.

shummershault by Scottbox360 October 2, 2008