Make:

KoolKat writes "Choppers aren't just for grownups, dude! In fact, with the abundance of little kids' bikes at yard sales, scrap yards and dumpsters, it only makes sense that this had to be done. Even brand new, a 12-inch wheel kids bike will only set you back a little more than 50 bucks. As for learning to ride a chopper, kids just don't seem to know the difference - they wobble around on the bike without a care in the world. Most kids that tried the small choppers that I made, could ride them on the first try. I guess if you're not used to a standard bicycle yet it may even be easier to master a chopper. Old dogs, new tricks, you get the idea." - Link.

Related:
Bicycle hacks, mods and how-tos - Link.