Can be dropped at any time to mean anything you want it to mean. Commonly used by high-level pokemon players and people with a high iq. Used similar to , . or even lol.
pokemaster420: Holy fuck I almost got ran over by a train playing pokemon gotoday god damn
memelord63419: mish
1) When one gets high, you tend to go on an adventure (or mission) to do go somewhere, usually in search of munchies. Mish is a short form of mission, and usually refers to this type of situation.
2) Another use of the word mish is to describe something that is far away.
1) "Yo man, lets go on a mish to get food!"
2) "Nah man, we aren't going to go all the way there...that is such a mish!"