a careful kusher is someone who smokes weed but doesn't want everyone to know. they want to maintain a good reputation and actually care about morals, but they don't mind getting a little #baked every once in a while
This is a word rooted in the many meanings for kush (refer wiki's Kush, kush, khush, kusher) that have arisen through history. Kushers are objects that mean different things to different people. Objects deemed as kushers usually provide happyness ('Khush' means 'Happy' in Hindi).
Objects may be Psychadelic (originating from the fact that kush is a very potent strand of marijuana). They may be violent (in a funny way). They could be awe inspiring or just interesting to the individual that deems the object a kusher.
Joe1 - 'Nice hat bro'
Joe2 - 'Yea its the only kusher that store had'
Jane1 - 'OMFG the fanglows as it spins?!'
Jane2 - 'Enough for you'
Jane1 - 'Ita kusherrrrr wooo'
Handsome Person 1: Hey have you ever noticed how kushermangenitous the food at Jack in the Box is?
Handsome Person 2: No
Handsome Person 1: Yeah me neither
Handsome Person 2: You said genit
Handsome Person 1: I sure did