You drink some, George. You take a big good drink.
I ain't sure it's good water.
Funny how you an him string along together.
What's funny about it?
Lennie never done it in meanness.
In the beginning of he book two men were traveling to their next job when they found a clearing when it got dark out. Lennie tells George to "take a big good drink." George tells Lennie that he doesn't think that it is good water. This tells us that George is looking after Lennie because he is worried that he might get sick. So no matter what you should always looks after your friends to make sure they don't get hurt or sick.
Slim thinks that it is funny how George travels with a guy like Lennie. George hears it and then protects Lennie. This characterizes George by George is a protective friend. This part foreshadows the end of the book by George protecting Lennie from the pain that Curly wants him to be in. So friends should protect each other from people trying to destroy them.
George and Candy find Curly's wife dead near the barn dead. They know it was Lennie. But George doesn't think that he didn't so it out of meanness. This foreshadows the beginning of the book when Lennie killed the mouse by petting it too hard. So this is saying that if you are petting something that you shouldn't pet it too hard.
Lennie runs to the bushes where George told Lennie to hide if he got in trouble. George told Lennie about the ranch that they would own by making him look across the river. George then shot Lennie in the head. This foreshadows earlier when Curly sent people out to find Lennie. Sometimes it's better to make the sacrifice yourself so the other one doesn't suffer.