People are x People is: Qual devo usar?

Aprenda a diferença entre people are e people is e em que situações se deve usar cada um das duas opções:

• People are
  Usamos are quando people é plural de um substantivo contável. People é plural de um substantivo contável ou seja usamos are para "people" quando falamos de quantidades como: 10%, metade de, um terço, um quarto, etc.
  
  • 10% of the people in the classroom are handicapped.
• People is
  Usamos quando nos referimos a um substantivo no singular. Veja que se referimos a uma só pessoa em um grupo, o substantivo no singular é one.
  
  • One of the people is Brazilian.

Usamos também are com quantificadores como: a lot, most of, a few, etc...

• Most of the people are happy.

Cf. Quando devo usar Are ou Is?

Abraços,

People is gonna laugh at me OU people are gonna laugh at me?

Is gonna be/laugh etc is used with singular, are gonna be/laugh etc, is used with plural.
When you say "...gonna laugh at me." the idea is of a plural or singular? Just a hint: when you use people referring to persons in general is singular in form and takes plural verb. That is, it´s plural most of the time.

Right... The ideia would be general, such as "If I do this people is/gonna laugh at me". Sorry but I didn't get it... I should use IS or ARE in this case? Thank u!

Now an example in Portuguese so you get the idea, if we say "se eu fizer isso as pessoas irão rir de mim" a idéia é coletiva (many people will).
Other examples in the same vein:

'Some people are going to leave, but that's not the end of your story. That's the end of their part in your story.'

“Other people are going to find healing in your wounds. Your greatest life messages and your most effective ministry will come out of your deepest hurts.”.

"People are going to behave however the social norms permit, and beyond that." - Max Cannon quotes from BrainyQuote.com

Again, when you use people referring to persons(1) in general is singular in form and takes plural verb. Then,... people are going to laugh at me.

(1) As in contrast to "people" the set of individuals that belongs to the same ethnic group, country, etc."

Now; an example of usage with people in the above sense: "If I do this, the American people is going to laugh at me." (it´s not people in general, it´s specified here).

Got it! Wonderful! Thanks a lot!

Mas e se a palavra "people" estiver fazendo referência a um povo, o que é diferente de "people" como plural de "person". Ainda assim fica no plural?

Ex.:

The Brazilian people (population) is wonderful.
Or
The Brazilian people (population) are wonderful.

What, then?

Could be both. Depending on whether you mean the word in the plural or singular sense.
Albeit you will think of it as a group/unit, most of the time. So, "are" is used in the sentence you have provided us with, also most of the time as well.

Ref. People, singular and plural

With the example they had given is the other way around, it´s more problable that you think in terms of one-by-one basis:
The Portuguese people have chosen a new president.