One of the guys I rode with, back in the day, was a serial tripjacker. He had a habit of accepting an invitation to go on a ride and then, after everyone had met up, changing the whole trip.
"Oh, you don't want to go to Mount Falcon...I know where there's this sweet trail that's a 25 mile loop, all downhill! You guys'll love it!"
"But," I'd say, "we only have 3 hours to ride."
"Oh, man. It's only 20 minutes away. It's so sweet! You guys would rather go there, wouldn't you?"
Of course, everyone would decide to change plans, despite my objections. Invariably, the "20 minute" drive would turn into an hour and a half, and the first two miles of the ride would involve 3000 feet of elevation gain while picking our way through baby-head rocks.
I finally got to the point that, when he would show up and change plans, I'd just make sure no one was in the truck with me, and then I'd go to the originally planned ride and ride by myself. After a while, a couple of my friends caught on, and would jump in the truck with me.
"We'll meet you there!" I'd call out the window of the truck as we left the parking lot. Then, we would drive to our original destination.
Eventually, I just stopped inviting the tripjacker along, and I stopped accepting his ride invitations.