balls up verb 2balls-up noun 1forms 4 verb2 •(UK, vulgar) To make a mess of a situation.He was putting everything he had into it, but he kept ballsing up. — 2009 •(UK, vulgar) To do something badly. To ruin a job.He really ballsed up that paint work. It'll have to be redone! balls-up noun1 •(slang, vulgar) Something which becomes muddled or botched in some way.I was making a cake but when I added too much sugar, it became the balls-up of my cooking career. formsballsed up · ballsing up · ballses up · balls-ups