Portuguese idioms literally translated sound amusing in English.  Below is a literal look at five common Portuguese idioms.

To feed a donkey sponge cake
Portuguese: alimentar burro a pão de ló

This idiom means treating someone well who does not deserve it.

Eating fish doesn’t pull wagons
Portuguese: comer peixe não puxa carroça

This implies that fish is not suitable food for someone doing manual labor.

Your neighbour’s chicken is always fatter
Portuguese: a galinha do vizinho é sempre mais gorda

This is equivalent in meaning to “the grass is always greener on the other side.”

An old donkey doesn’t learn languages
Portuguese: burro velho não aprende línguas

The equivalent in English is “you can’t teach an old dog new tricks.”

Searching for horns on a horse’s head
Portuguese: procurar chifre em cabeça de cavalo

This idiom does not have an equivalent in English. Searching for a needle in a haystack is closest in meaning but not equivalent because the ‘needle’ in question exists and may be located, while a ‘horse’s horns’, do not.

Source:
Oxford Dictionaries