When someone are on a mission to buy weed or hash for you, it's polite to give them some of the stash as payment for the job. This little part is the stresseflis.
Her er bønna di, kan du bite av ei lita stresseflis til meg?
Doctor: The diagnosis isn't good.
Relative: what seems to be the problem?
Doctor: Your friend suffered from a level 4 STRESSPLOSION. His shattered dreams may leak into the air vents, we have to seal the room.
Relative: Damn that sucks.