When one takes a marshmallow and rests it on anothers anus, and then forcefully insterts it using a penis. This continues until the anus is almost completely filled with marshmallows.

Marshmallow creme may be used as lubrication, but anal lube is a definite no go, since the marshmallows will eaten out of the asshole afterwards.

Got the covid-19 vaccine

Marshing (Extreme Marshmallowing): The art of catching a marshmallow in your mouth in the most physically creative way possible.

To spend an extremely large amount of money on one single event.
Involving lots of meat, and a ton of extra food.
To over do something drastically.

holding the marshmellow over the fire until it becomes crisp, hot, sticky, and delicious.