Matt 22:2-14 "The Kingdom of Heaven is like a certain king, who made a marriage feast for his son, and sent out his servants to call those who were invited to the marriage feast, but they would not come. Again he sent out other servants, saying, ‘Tell those who are invited, "Behold, I have made ready my dinner. My oxen and my fatlings are killed, and all things are ready. Come to the marriage feast!"‘ But they made light of it, and went their ways, one to his own farm, another to his merchandise, and the rest grabbed his servants, and treated them shamefully, and killed them. When the king heard that, he was angry, and he sent his armies, destroyed those murderers, and burned their city. "Then he said to his servants, ‘The wedding is ready, but those who were invited weren’t worthy. Go therefore to the intersections of the highways, and as many as you may find, invite to the marriage feast.’ Those servants went out into the highways, and gathered together as many as they found, both bad and good. The wedding was filled with guests. But when the king came in to see the guests, he saw there a man who didn’t have on wedding clothing, and he said to him, ‘Friend, how did you come in here not wearing wedding clothing?’ He was speechless. Then the king said to the servants, ‘Bind him hand and foot, take him away, and throw him into the outer darkness; there is where the weeping and grinding of teeth will be.’ For many are called, but few chosen."  (web)

The ones he invited but didn't come represent the Jews in general. Of course there were a remnant who did come, like the apostles, but the Jews as a whole rejected the gospel even to this day. Notice he says, "those I invited did not deserve to come." But if they didn't deserve to come then why did he invite them? Because it was in their rejecting of the invitation that indicated they didn't deserve to come. The invitation should be given to all, but those who deserve to come are those who respond to it properly. The people on the street corners are strangers whom you wouldn't normally invite to a wedding feast. They represent the Gentiles, whom the Jews despise. And not just those Gentiles who may be reckoned good, upright citizens, but also the bad. The invitation is given regardless of one's moral behavior.

However, this is not to say that the guests can show up dressed however they like. If you come dressed inappropriately, then you're not really into the "spirit" of the wedding. When you receive such a wedding invitation, it goes without saying that the host expects you to receive it in the right spirit. So also with the gospel.This concept is much along the sames lines as the parable of the sower. Those who received the word with an honest and good heart "Produced fruit in keeping with repentance." Mt 3:8

But what are these wedding clothes? They are the expressions of our faith. The Bible often associates them with Christian behaviors and attitudes.

Ro 13:14 Rather, clothe yourselves with the Lord Jesus Christ, and do not think about how to gratify the desires of the sinful nature.

Col 3:12 Therefore, as God's chosen people, holy and dearly loved, clothe yourselves with compassion, kindness, humility, gentleness and patience.

1Pe 5:5 Young men, in the same way be submissive to those who are older. All of you, clothe yourselves with humility toward one another, because, "God opposes the proud but gives grace to the humble.

Rev 19:7-9 Let us rejoice and be glad and give him glory! For the wedding of the Lamb has come, and his bride has made herself ready. Fine linen, bright and clean, was given her to wear. (Fine linen stands for the righteous acts of the saints.  Then the angel said to me, "Write: 'Blessed are those who are invited to the wedding supper of the Lamb!'

The place of weeping and gnashing of teeth is mentioned a number of places.

Darkness

Mt 8:12 But the subjects of the kingdom will be thrown outside, into the darkness, where there will be weeping and gnashing of teeth."

Mt 22:13 "Then the king told the attendants, 'Tie him hand and foot, and throw him outside, into the darkness, where there will be weeping and gnashing of teeth.'

Mt 25:30 And throw that worthless servant outside, into the darkness, where there will be weeping and gnashing of teeth.'

Mt 13:41,42 The Son of Man will send out his angels, and they will weed out of his kingdom everything that causes sin and all who do evil. They will throw them into the fiery furnace, where there will be weeping and gnashing of teeth.

Mt 13:50 and throw them into the fiery furnace, where there will be weeping and gnashing of teeth.

Mt 24:51 He will cut him to pieces and assign him a place with the hypocrites, where there will be weeping and gnashing of teeth.

Parallel passage:

Lu 12:46 The master of that servant will come on a day when he does not expect him and at an hour he is not aware of. He will cut him to pieces and assign him a place with the unbelievers.