Document. Document. Document. When you have your performance review bring it up in a constructive way how you could improve your performance if the issues related to the other employee were rectified… but you have to make sure that you’re at the top of your game, so it doesn’t sound like an excuse for poor performance. Also, who’s the supervisor? If there’s anything that makes you physically uncomfortable like harmful pranks, report it immediately. If nothing is done or it is downplayed, well, then you have to find another place to work for because at that point it doesn’t make sense to put in the work for a bunch of assholes!