Some of the coolest optical illusions that I came across are noted in this blog.
what is the hidden object and where is it?
if u look upside down its reflection is congruent on both sides
What object you fucker
Turn the page sideways. From one end it is a man. From the other end it is an owl
Also there is a man praying in the middle. Turn the page sideways. THere are probably others that I don't see.
And I saw an arrow in the middle which cut across the praying man