It's a very fun tradition. My son especially likes to ring and run. You can buy bags with tags on them already. I decided to alter one of mine. I am also going to make 9 more to put in the treat bags so my son's friends parents don't have to make them.
I was at Target the other day, and all their premade "boo" stuff has monsters on it, so I chose Joe the Monster.
Here's what the back looks like- cute little poem. I've included it so you can copy if you like.
Have a great day!