This is one of the funniest, but also clearer expressions we have. The translation is "What is a fart, to someone who is soiled". It has similar meaning to "it can't get any worse".
It means that since you are already in a bad situation (like having crapped your pants) smaller things won't make much difference (like farting in this case).
- Nossa, ela bombou e ainda pegou a maior chuva na volta da escola.
- Bah, mas o que é um peido pra quem tá cagado mesmo né?
Another abbreviation of você (you), like cê.
- Ocê sabe que horas são?
- Pelo sol, são quase duas.
Same as "Say cheese!", used by photographers to alert they are about to take a picture.
- Olha o passarinho!