A fisting party. When two or more gay men fist eachother simultaneously.
"Kevin had his hand in Lance's ass. Then Roderick started fisting Kevin while Josh fisted Roderick. Once Lance lubed up his hand and stuck it in Josh's asshole it became a full-fledged soulercoaster."
When gay guys fist one another. Group fisting.
"His hand is in your ass and my hand is in his ass and your hand is my ass. Woo hoo, we're soulercoasting now!"