Get some cheap cars at the Dollar Tree the amount you will need for the boys coming. Get out some pencils and tie string or yarn to the car, hide it (under a couch, whatever, and then make a spider web and tie the other end of the strings to the pencils and keep them by the doorway to the room. Have the boys roll up the string on the pencil to receive the hidden car on the other end. We did this when I was a child and for for my children, we are now doing it for the grandchildren. They love it!!
Take 5 mixing bowls and line them up a foot apart. Have the boys try to throw a soft ball into the bowls one at a time, the winner is the one who can toss the soft ball into all of the bowls and have it stay in.
If you have an even number of boys you can have them run a three legged race.
Good luck and have fun.