Scuttle in the Mouth 

Origins found in Yorkshire saying 'coal-scuttle in the mouth', though shortened through Cumbrian slang.
Traditionally used as a reposte to an insult, equivalent to the unpleasant experience of physically trying to put a coal scuttle in your mouth.

Alternatively can be abbreviated to a simple 'Scuttle'.

"She told me I was ugly and that was a right scuttle in the mouth"

"Danny shagged my mum, what a scuttle."

Scuttle in the Mouth by vianicolodi February 26, 2010

banger in the mouth 

Synonymous with sausage. This is a fake Britishim, popularized by David Cross's character, Tobias Fünke, on the television show Arrested Development. One of many references to Tobias's latent homosexuality.

Who wants a banger in the mouth?

banger in the mouth by Funkdubious2 December 7, 2006

Look a gift horse in the mouth 

It's Roman slang: "Noli equi dentes inspicere donati". For example, you can find it in St. Jerome's Commentary on the Epistle to the Ephesians, written in the 5th century.

You look in a horse's mouth to determine its age and/or health. So if someone gives you a horse, and you look in it's mouth, it's like looking for a price tag. It's rude!

Lucius: I bought you this tunic in Thebes for your birthday.
Quintus: Thanks dude. Hey, look, the seam has really cheap thread.
Lucius: Noli equi dentes inspicere donati.
Quintus: Wha?
Lucius: It's Latin. Don't look a gift horse in the mouth.
Quintus. Oh yah, right. Mea culpa.

Look a gift horse in the mouth by Ed the Horse July 17, 2009

frothing at the mouth 

An insult or description of someone who is so enraged about something they lose it and start acting like a insane person. Out of control. Similar to a rabid animal.

She was so angry she was frothing at the mouth.

frothing at the mouth by ihatecreatingpseudonyms February 8, 2017

Look a gift horse in the mouth 

to be critical of a present or gift

Despite thought put into the gift, he decided to look a gift horse in the mouth and commented on the cheapness of the gift

Look a gift horse in the mouth by stanzz October 25, 2006

pop off at the mouth 

To get carried away in one's speech, usually in regards to talking about someone else or some action one is going to do. Basically talkin' mess taken too far.

After a few too many drinks at the party last night, Joe really started to pop off at the mouth. First he started talking about my physique, then about how he could beat me in a fight.

pop off at the mouth by Dann326 March 4, 2016

cock-in-the-mouth 

asshole, jerk, loser; clusterfuck.

Pl. hotly debated whether plural form is "cocks-in-the-mouth" or "cock-in-the-mouths".

Did you have you review with that cock-in-the-mouth boss of yours?"; "Yes, I would change lanes if this cock-in-the-mouth would get out of my way."; "St. Patty's day in NYC is one gigantic cock-in-the-mouth.

cock-in-the-mouth by joebohobitz April 17, 2011