粵典 (words.hk)香港詞
引申指喺學校學嘅嘢好似屎咁冇用 (to have learnt nothing but crap from school; literally: to study the nappy)
動詞用例
你連乘數表都唔識，你讀屎片㗎？
nei5 lin4 sing4 sou3 biu2 dou1 m4 sik1, nei5 duk6 si2 pin2 gaa4?
Can't you do multiplication? Didn't they teach this in school?