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!"