Crookes Tube Puns

This was a problem on my step sons homework. No matter what, he couldn't seem to grasp it. So, I grabbed some post-it notes, turned it to a diamond and said "this is a diamond correct?" he says yes. I then turn the post-it notes a few degrees and say "this is a square correct?" And he instantly got what he had to do. I then threw out this, grade "A" knee slapper of a line "Diamonds are just crooked squares, you can't trust'em".

I think I'm gonna put on my jorts and tube socks now.