Have you ever had a co-worker on a job site that does more damage than good?
I know how annoying these people can be (I used to be one) and sometimes you can't just go up to the foreman and have them fired since they are the bosses nephew or something just as useless.
Well here is yet another way to get rid of them for a while.
Call the new co-worker over and tell them the piece of wood you are working on is too short and you need a board stretcher. Tell him to run over to a rental place and pick one up.
This is how you can tell if the rental guy has a good sense of humor. See if they refer your coworker to another rental place. With any luck, you can have the co-worker driving arounf all day long looking for a board stretcher.
Just because you get stuck with someone worthless doesn't mean you can't have fun at their expense.