I dont know whats the age of your kids, but if they are old enough you can do this:
1- rent a wheelchair
2- disguise yourself as a greatly injured person, with bandages all over your limbs and body, add some fake blood to make it even funnier

3- have the kids roll you around
When i was a kid we actually did this (dad had a broken leg and wouldnt have allowed us to do the halloween run without an adult escort). Was great fun

Carole