bloomer
bloom·er / ˈblumə ; ˈblu:mə /noun
1. bloomers pl.underwear that women wore in the past, like loose trousers that end at the knees〔过去女士穿的长及膝部的〕宽松内裤
2. CBrE old-fashioned an embarrassing mistake that you make in front of other people – used humorously〔在大庭广众前犯的〕错误，差错，洋相〔幽默用法〕;SYNblooper AmE