Though my kids will still drink juice boxes and Koolaid, they love to have "pop" or cans of soda when they have friends over or for a special treat. Wet cans of pop don't lend themselves to being written on with markers and kids are famous for setting down a can and forgetting which one is theirs. They are also famous for not wanting to drink from a can unless they are SURE it belongs to them!
Rubber bands to the rescue (unless you are from Pittsburgh, then you would call them "gum bands"). I like to think of this as a red neck wine charm!
Save your fat bands (often I save them from produce like broccoli and lettuce) and write each child's name.
Slip the band over the can and it's marked!
You can also use this method for keeping track of the number of soft drinks they have had by marking a little hash mark beside their name ... just in case your kids are like mine and try to fib about how many cans they have had. They won't even notice the mark and will wonder just how you knew they were asking for a 3rd can!