"What is the chicken for?"
Translation:Para que é o frango?
There are four main types of situation in which it is more natural to end a sentence or clause with a preposition:
• passive structures (she enjoys being fussed over)
• relative clauses (they must be convinced of the commitment that they are taking on)
• infinitive structures (Tom had no-one to play with)
• questions beginning with who, where, what, why... (what music are you interested in?)
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Just a note that this was written at the end of the opinion-based article that was linked. Sounding natural and slang uses do not change the order of proper English grammar.