The funny thing about idioms is that sometimes its literal meaning is totally absurd and non-sense. That is visible in “Pequeno dicionário ilustrado de expressões idiomáticas” - “The little idioms illustrated dictionary”. Below you can see a couple of the images:
Sem pé nem cabeça Pagando o pato
To check more images visit http://imasters.uol.com.br/artigo/3220
Check the meaning [...]