louse up Meaning to spoil something or make it fail For example She really wants this job, so I hope she doesnt louse up the interview. Dont worry. He wont louse it up. Hes been doing these deals for years. #Slang_of_the_Day ▬▬▬▬▬▬▬▬▬▬▬▬ ➠@PhrasalCards ➠@SlangWords ➠@IdiomsLand ➠@Vocabulix ➠@GrammarCards ➠@EnglishGate ➠@StoryPage 2.9K viewsedited 15:30