douchecanoe

a crappy person
someone who has wronged you
a fool
someone who does dumb things
a word to call somebody when ur in public and must refrain from saying words that are less socially acceptable

"Your friend is such an idiot! I can't believe he just put his dick in a sheet of pastry and walked around the room yelling "anybody want a sausage roll??!!!"
He's such a Douchecanoe!!"