My mom keeps her brother, my uncle, with her because he is mentally handicap and cannot live on his own. He was born breech and the oxygen to his brain was cut off which caused the handicap (this is what I was told, but 3 of her 5 children are this way).
We call him "Buddy". He is 45 now and since I was a little kid I always remember him being exactly the same.
He has the mentality of about a 9-year old, which is perfect for my boys, 7 and 9. I remember when I was their age, Buddy was the best playmate. He loves video games, he's very outgoing, but the best thing is he is an adult and has the strength and size of an adult. He was the best to play with. He could lift us up into trees and cut branches for us to build things with.
And it's just funny to see him playing with my kids the same way as when we was little. Usually, your childhood friends grow up with you. Not Buddy, he will always be a childhood friend to children. He stays with us most weekends because my mom works and is gone from Fri until Mon morning and he can't stay by himself that long.
He's great company for adults too. It's fun to watch scary movies with him, he gets scared but at the same time thinks it's hilarious and will laugh his ass off. Everything is funny to him, he is always smiling/laughing.
Now his brother, Edward, is the opposite. He is just as mentally handicap as Buddy, but maybe even a little worse. And in a very violent way. He is always in jail, he likes knives and he likes to break things. I wouldn't allow him to stay overnight at my house. A short visit is the limit with him, he's 6'4, 250 lbs and scary to me. Very unpredictable.
Anyway, here is Buddy with my 2 boys and their friends.