The definition of "mircogoon" or "microgooning" is an action. Microgooning is a form of gooning/playing with your penis that involves using your index finger and middle finger as chopsticks around the base of your penis and "flicking" it at mock speeds.
Microgooning can also be used as a celebration. For example when getting a kill in a online video game to celebrate you can hit a quick mircogoon. The better the clip the faster the flick.
Yo Noah, I just chudmaxxed my mircogooning skills last night Noah: That's lit I know your index finger and middle finger sore asf
Ya twin
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That's a clip *starts microfapping*
Im microgooning