I'm also thinking of "As I was going to St Ives, I met a man with seven wives. Seven wives had seven kids, seven kids had seven cats, seven cats had seven kits, kits, kids, cats and wives, how many were going to St Ives?"
Could be cryptic with "Meet me on the way to St Ives" or something like that - maybe someone else has a good idea for how we can use this well-known riddle?
Or maybe a picture of a puzzled man walking to St Ives (signpost), seeing a man with only two wives and a couple of kids, with the slogan "Working on it"!