Questions on a few phrases
1. 쩗은 사람들 사이에서 꽤나 유행했다
꽤 is rather, so here what does it mean by 꽤나 ? is it a bit different from 꽤?

2. 시끌벅적하게 떠들며 마셔야 제 맛이거든
I want to ask the meaning of 제 here. None of the meaning from the dictionary seems to fit the meaning here, I thought about the meaning of "the most"? but I can't find that option in daum/naver dict.

3. 말없이 있을 수만은 없지만
I don't quite understand this phrase.

Thanks!

Question

Questions on a few phrases
1. 쩗은 사람들 사이에서 꽤나 유행했다 
꽤 is rather, so here what does it mean by  꽤나 ? is it a bit different from  꽤?

2. 시끌벅적하게 떠들며 마셔야 제 맛이거든 
I want to ask the meaning of  제 here. None of the meaning from the dictionary seems to fit the meaning here, I thought about the meaning of "the most"? but I can't find that option in daum/naver dict.

3. 말없이 있을 수만은 없지만 
I don't quite understand this phrase.

Thanks!

Answer

-나 is an particle used after an adverb for emphasizing the degree or quantity. 
꽤나 means "quite, rather, fairly" as like "꽤" and has a nuance of exclamation.

제맛 is one word means "the original taste of a food, the original feeling of something"

말없이 있을 수만은 없지만 = 말없이 있을 수만은 없다. 그렇지만
말없이 있을 수 있다 means "I can keep silent"
말없이 있을 수만은 있다 means "I can only keep silent"
말없이 있을 수만은 없다 means "I cannot only keep silent"

말없이 있을 수만은 없지만 means
I cannot only keep silent. Though

Answer

1. 젊은 사람들 사이에서 꽤나 유행했다.
In this sentence 꽤(나) means "quite" or "pretty".

2. 시끌벅적하게 떠들며 마셔야 제 맛이거든.
제 in this sentence means "own" or "well done".

3. 말없이 있을 수만은 없지만.
I can not keep a silence but..
I can not keep my mouth closing however..
I can not be without any speaking but..