Chłopcy, that word remind me one of the best Polish moves "Chłopaki nie płaczą". https://www.youtube.com/watch?v=3doOHc0xjok

Strait from the factory...

new kids in the neighbourhood? new students in school?

It isn't that way for the same reason this is wrong: "Cats likes milk." It isn't about matching the ending letter to be identical.

Most words that end in a consonant are masculine. You can also check them in a dictionary to make sure. The adjectives usually end in i or y.

So if it is masculine, you have:

• Nowy but, nowy kot, nowy chłopiec, nowy komputer
• Słodki chleb, słodki pączek, gorzki melon…
• But you also have some exceptions, like nowy mężczyzna

And most words that end in a are feminine and the adjective ends in a:

• Nowa wódka, piękna kobieta, słodka babeczka
• Some exceptions include mysz (Ta ładna mysz lubi ser)

And neuter words usually end in e, o or (rarely) um and the adjective usually ends in "e." Plural nouns of any gender almost always take the same adjectives, but there is an exception for that too.

• Nowe koty, nowe komputery, słodkie pączki, piękne kobiety…

But if it is a masculine personal noun, like "ludzie," it has a new ending using "nowi" or "nasi"

This one is still a bit new to me but I hope the others helped

It's all down to the fact that "chłopcy" is what's a masculine virile noun, in other words it describes a person, not an animal or an object. So while "chłopcy" and "buty" are both masculine, they have different adjectival endings because of this _virility.

I hope this makes sense.

I'm quite new in Polish but I guess that it helps to differentiate singular ("nowy/nowa") and plural ("nowi/nowe") forms of adjectives. "NowY buty" will sound approximately like "two new shoe". "Nowy" can be only one "but". Adjectives don't have the same endings as nouns. It just a coincidence that plural noun ("buty") and male singular adjective ("nowy") have the same ending "Y". If I'm wrong, correct me please.