Child abduction is not funny, but this will be.
I've seen some sketchy ice cream truck drivers in the Cincinnati area and have always wondered which are for real and which are secretly out to steal unsuspecting children and their $2 in quarters.
Heres what you do:
Get a crappy looking ice cream truck. Get one of the creepier looking guys to drive it. Plant a child on a street corner/ busy area (similar to the child in the bad grandpa sketch). Truck pulls up innocently. Kid goes to get ice cream. Ice cream sales person goes to hand child ice cream and pulls him/her through the window into the truck, child screaming, guy yells "drive, drive!" or something that will catch people's attention and drive away. See what happens.
:) good luck!