What is Cum-gargling?
1.
To wash or rinse the throat or mouth with cum held in the throat and kept in motion by a stream of air from the lungs. Can be used as part of an insult to someone jokingly, or to a person of which this actually describes.
"Dude, you're such a cum-gargling gutter-slut!"
or
"Shut up you cum-gargling thunder-cunt!"
See