a dutchman's blow - Blowing snot out of one nostril like you’re a snot sniper, a

Blowing snot out of one nostril like you’re a snot sniper, and your hand is the shield blocking the other side.

He did a Dutchman’s blow in the middle of a meeting. Everyone was distracted.

I did a Dutchman’s blow on the bus. The kid next to me got snot in his drink.

She did a Dutchman’s blow in the kitchen. My dad was horrified.