I had an entire world that I used to visit. Unfortunately it was called "PoofyLand", much to the amusement of my family. It completely disappeared the day my sister "helpfully" drew me a map of it (how she imagined it). I never found my way back there, though I tried and tried. sob.
later on I had a huge colony of multicoloured "ants" that went everywhere with me. It drove my parents mad when they had to wait until all my ants had got in before they could shut the van doors. I very genuinely saw these ants, and I think it was probably a vision problem.