I thought these next two examples were amusing.  Take two equal sized coffee cups and stack them like in the Jastrow illusion.  Naturally, we'd want to drink the one on the bottom since it looks larger than the other!  The other picture is one of three equal-sized cats stacked on top of each other, but looking at them, it seems the one on top  is the smallest one, which could be interpreted anywhere from a cat falling to the ground and the other 'cats' are shadows to three cats stacked on top of each other with the 'smallest' cat on top.