when you're about to bust and you press your urethra against someone's nostril, letting it fill up their nasal cavity. If it's a fat load, it can squirt out the other nostril, giving the appearance of a gogurt tube being squeezed dry.
"Fuck man I gurted Bryan the other day and it was insane! It shot at least 2 feet out of his nose."
"Wanna go gurting after school? Don't worry, you can gurt me back after"