Fouls up is a colloquial term that is used to describe a mistake or an error made by someone. The term is often associated with sports and is typically used to describe an action that undermines or interferes with the progress of a team or a game. There are several synonyms that can be used in place of fouls up including botch, bungle, mess up, flub, and mishandle. All of these terms refer to a mistake or an error made by someone, and they can be used interchangeably with fouls up depending on the context in which they are being used.