horse's ass
noun [ C usually singular ] US offensive uk/ˌhɔː.sɪz ˈæs/ us/ˌhɔːr.sɪz ˈæs/
蠢货，傻瓜
a stupid and annoying person
You may think you're being funny, but everyone else thinks you're being a real horse's ass. 你可能自以为很风趣，可是所有人都认为你是个傻瓜。