Tjomp

Tjomp (IPA: [t͡ɕomp] or [t͡ʃɒmp], see Pronunciation below), also known as "break" or "glitch" is a term referring to the act of leaving a team (e.g. by destroying wand or barrier creator) after the portal has opened, before any players have joined the portal. This allows other players to play with fewer than 4 players.

If one leaves the team at the exact same tick as the portal opens, one does not receive a 10-minute penalty.

This can also be done in between between altars (e.g. when Air altar is over, after the portal has opened, before players have entered into Mind altar) by destroying one's wand after the portal has opened but before players have entered the portal. By doing this correctly, you prevent the game from ending, but you are still given a penalty. The duration of the penalty you get is 4 minutes shorter than the time left in the game you just left.

Another way to allow players to play GOP with fewer than two players on each team is to have some players sit the game.

Pronunciation
The exact pronunciation is currently being discussed in the comments.

The term "tjomp" was coined by the GOP player Timome, who is a native speaker of Norwegian and gave the word a Norwegian pronunciation and transcribed it in Norwegian orthography. The pronunciation is transcribed in IPA as follows: [t͡ɕomp]. For those who have trouble pronouncing "tjomp" according to the "official" pronunciation, the word may be pronounced like "chomp" (RP: [t͡ʃɒmp]; GA: [t͡ʃɑmp]).

Detailed phonetic analysis
The "tj" represents a voiceless alveolo-palatal affricative (IPA: t͡ɕ), pronounced like the "ch" in "chalk". The "o" transcribes a open-mid back rounded vowel (IPA: ɔ), which is pronounced as the vowel in Received Pronunciation "caught" or General American "more". The "m" and "p" are pronounced more or less as in English.