wow are you sure? I've cried in many locations but to no avail =S buuut I guess I'll keep trying. -__-
For 97 yea I'm positive, set those blue blobs on fire in Marijuana Goddess and found those blue/pink things in amusement park with the teleporting TV's. The only object I have probably never seen is that flower pot with the heart next to the farmer.
Like above me, a lot of people claim to have seen every object but have still not recieved the wallpaper.