A reference to a zen koan, worn threadbare and meaningless by endless repetition in the media. It has no 'answer' unless, as in definition (1) above, the answerer redefines the term 'clapping', thus entirely missing the point.
Teacher: "What is the sound of one hand clapping?"
The sound of one handclapping is the sound of one hand closing quickly.
The sound of one hand clapping is supposed to be a question with no answer. It is a clasic Zen koan given to students to aid in enlightenment by leading the mind into a cul-de-sac with no way out but enlightenment. How enlightened could the person who came up with this koan be, considering it has such an obvious and simple answer?
Fundamental lore of Zen Buddhism; know as the Kōan traditional. In the west formally termed onanism or colloquially: ‘throttling the purple headed yogurt slinger’. This is the sound of skin slamming skin as “mediation” reaches the point of enlightenment.
“If you’re doing nothing, why can half the building hear the sound of one hand clapping? I swear if you’ve ruined another one of my Grattan catalogues with your man milk I promise you this is the last time Madame palmer's five daughters are coming 'round to play.”
Any period of time where you and your friends go out without initial purpose or expectations. Usually in the early hours of the morning or late at night, side quests last as long as everyone is still out away from their home, dorm, or common meeting space. Side quests usually happen after a "main quest," scheduled hang out or party and usually feature less people than the original main quest.
"I'm bored but idk what to do... wanna just go out?"
"Hell yeah man let's go on a sidequest!"
A group of people that rolls 600 pounds deep, which is really no different than if one person acted like the 600 pound gorilla all by themself, it's just bullying spread around a group to fuck with somebody. Just like each person has an asshole, and to some degree is an asshole, a collective 600 pound gorilla has a collective asshole so that no one person has to take responsibility for being the asshole or the one who said this or that.
The collective 600pound gorilla was punching its chest, showing who the alphas were.