Hmmm...
How about
:
Horse for sale: a real packer (draw a horse carrying luggage)
Horse for Sale: Great kid's horse (draw like 10 kids on his back) I actually did draw a cartoon once of one of the school horses with like 5 kids on his back, one was braiding his mane, another was braiding his tail, another was picking his hoof and another was holding an apple up towards his nose
This is a cute idea. It does remind me of a series of cartoons I drew when I was like 12 of all the school horses (including the one above) to showcase their individual personalities.
Have fun with this project. I'll post more ideas as I come up with them.