What is Douchish?
1.
Like a douche in many ways
Cassidy is a douchish person because he stole my word.
See
2.
The act of being a douche; The act of being an asshole.
If someone where to throw you in a trashcan then laugh and leave, that'd be douchish. Or the best example of all, if someone were to not even acknowledge your presence because of the people they hang out with. (Or if you tried to break up a perfectly fine relationship for your own benfit, you'd be acting douchish.)
See