#1:
Count the black dots!!! (from LiquidGeneration.com)

#2:
How many legs does this elephant have? (from LiquidGeneration.com)

#3:
The squares marked A and B are the same color. Proof... (from LiquidGeneration.com)

#4:
This one is really weird!!! (from ritsumei.ac.jp)

#5:
Move your head back and forth to make a cool wave. It works best from far away. (from ritsumei.ac.jp)

#6:
The vertical bars are the same length!!! Proof... (from torinfo.com)

#7:
This crate is totally impossible to build, as you can see if you look closely. (from torinfo.com)

#8:
These lines are perfectly staight!!! Proof... (from eyetricks.com)

#9:
The center circles are exactly the same size!!! Proof... (from eyetricks.com)

#10:
The pink squares in each diagonal stripe are the same shade of pink! Proof... (from eyetricks.com)

#11:
How many prongs does this fork have? (from eyetricks.com)

#12:
The diamond is perfectly straight!!! Proof... (from eyetricks.com)

#13:
These steps keep on going and going and going... and always up! (from eyetricks.com)

#14:
Line A-B is the same length as B-C! Proof... (from eyetricks.com)

#15:
The three blue squares are perfectly straight!!! Proof... (from eyetricks.com)

#16:
Stare at the center and move your head closer and farther away from the screen. (from ebaumsworld.com)

#17:
How many shelves are there? (from eyetricks.com)

#18:
The top lines of each shape are the same length!!! Proof... (from eyetricks.com)

#19:
These two bars are the same length! (from eyetricks.com)

#20: Read the following paragraph:

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Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

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#21:
The two curved sections are the same shade of gray!!! Proof... (from web.mit.edu)

#22:
There is only one shade of gray in this picture!!! Proof... (from web.mit.edu)

#23:
The two small rectangles in the center are the same shade of grey!!! Proof... (from web.mit.edu)

#24:
Does this look like a spiral? In reality it is a bunch of concentric circles! (from psycharts.com)

#25:
Does this picture make sense? (from psycharts.com)

#26:
Read the color, not the word. (from psycharts.com)

#27:
Look at this impossible nut. (from psycharts.com)

#28:
Scroll up and down and watch the center square move. (from ebaumsworld.com)

#29:
Look at this impossible triangle. (from psycharts.com)

#30:
These two monsters are the same size! (from psycharts.com)

#31:
Look at these walnuts! (from ebaumsworld.com)

#32:
The purple lines are perfectly straight! (from ebaumsworld.com)

#33:
Are these arrows facing inwards or outwards? I don't get it... (from ME!!!)