It's a lightweight craft used by douches to move around on the figurative conversational currents to spread their message of doucheness to new individuals who were blissfully unaware of their existence. It also has cupholders, which is the only redeeming quality of the douchecanoe.
"Wow, did you hear what Jim had to say at the party last night?"
"Yeah, he came from nowhere on his douchecanoe and made everyone feel uncomfortable."
Someone who is so much of a douchebag that the pressure built up inside of them releases. Spewing from the mouth, in a thread of molten douche.
Dont be a lard slop DOUCHECANOE.