An establishment, generally a public bar or club but could also be a private residence, which is frequented primarily by douchebags.
Residents of a douchebag fort can also be given rank based on their level of douchebaggery.
"No, I don't want to go to the Kells, it's a total douchebag fort."
or
Jill, you really donโt want to date Kevin; heโs a Sergeant at Fort Douchebag."
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