Exodus 24:3-8
3Moses came and told the people all the words of the Lord and all the rules. And all the people answered with one voice and said, “All the words that the Lord has spoken we will do.”4And Moses wrote down all the words of the Lord. He rose early in the morning and built an altar at the foot of the mountain, and twelve pillars, according to the twelve tribes of Israel.5And he sent young men of the people of Israel, who offered burnt offerings and sacrificed peace offerings of oxen to the Lord.6And Moses took half of the blood and put it in basins, and half of the blood he threw against the altar.7Then he took the Book of the Covenant and read it in the hearing of the people. And they said, “All that the Lord has spoken we will do, and we will be obedient.”8And Moses took the blood and threw it on the people and said, “Behold the blood of the covenant that the Lord has made with you in accordance with all these words.”
This is Israel only months out of Egypt. They're still fresh from that existence, it is all they have ever known, and they have no national identity. So, in the chapters previous, God has listed out some rules for this people of His, so that they may live in a way that reflects the way that He thinks.
Some of these rules seem really really basic and pretty obvious to us. Ex. don't spread a false report, or if someone borrows something and breaks it, they have to pay it back,. Some are a little strange, we don't really understand what they meant to the people or exactly what they are pointing to about the character of God. Ex. some of the rules about slaves come across pretty strangely in a world trying to make equality of all men stick as a universal social norm.
So after spending relentless hours in preparing to meet the Lord and conveying His messages, Moses brings these things before the people and requires them to officially "sign" the covenent in a manner of speaking. The people join in one voice agreeing to God's terms, an "I do" on their half of the relationship. Then Moses takes the blood from the sacrifice and throws half on the alter, to God, and throws the other half on the people.
Moses throws a bowl of blood on the people.
I really enjoy this part. I think its because of the countless numbers of church-goers who would be shocked and angered by having a huge basin of blood thrown across them at church.
"Well that was just totally unnecessary!" they would all mutter under their breath.
Its funny how easily people would be upset by this, completely overlooking the significance. The Bible says nothing about the people being indignant, although I think this could have been a pretty hilarious event to watch if it wasn't so serious. Its sad to ever make a statement like this, but God would probably never be able to get away with a stunt like this with most modern Christians.
Think of all the amazing implications involved though. These people were not just agreeing to some list of rules. It wasn't just a promise not to cheat buisness partners or treat neighbors better. This was a serious event, something died for this agreement to be made. And the people were linked physically by this blood with God, symbolically through His alter. But here's the thing that really stuck with me so greatly. The people were wearing the covenent.
This blood was closer to them than their clothes.
It didn't just affect their lives. It wasn't just a part of everthing they did.

They were physically coated in the covenant.