I insist. It is a very polite way of saying that you insist on doing some favor.
You can use it when you want to let someone else to sit on your place (like on buses, metro, etc) and s/he denies saying that she isn't tired or doesn't need.
Similarly, when you volunteer to do something and others say that you don't need to. You just say "Faço questão", or "Eu faço questão", and they will understand that you really mean it.
- Ih! Esqueci o boleto lá em cima!
- Pode deixar que eu pego.
- Ah, não precisa não. Deixa pra lá.
- Pode deixar. Faço questão.
To talk like a parrot, talk too much.
- Você encontrou a Josiane ontem?
- Encontrei, mas ela fala que nem um papagaio. Parecia até mais um monólogo que um diálogo.
A "redneck" who goes to the beach for a day, brings his own food and has no consideration for anyone else around. He/she generally are the typical light-skinned irritating day tourists that crowd the beaches in Brazil.
It has turned into a term to describe people who are inconsiderate to others and don't want to fit in.
Those farofeiros who are always eating chicken with farofa, make so much noise, don't clean up after themselves and have no consideration for other people!
João is such a farofeiro, he could care less about anyone else around him!
- Por que a Mônica tá fazendo bico?
- É porque o Cebolinha pegou o coelhinho dela de novo.