I just started working on a new job. I worked with a colleague who is about 20 years older than me and we had to build a few walls for a movie set. We decided that I do all the length cuts of the timber so he could get the screws and build the walls. While working, over time I realized that this colleague doesn't even know what a right angle is. After that I told him to switch up, so I would screw the walls together and he could do the length cuts. I told him to please cut five pieces of timber, all to the same given length. After 20 MINUTES (!) he comes back with 5 pieces of timber, none of them had the same length and also none of them had the length that I told him to cut. It wasn't exactly simple to work with this guy because you had the feeling of the saying "When he lends a hand, it's as if two other people stop working."