When you go take a poo that looks normal in the bowl but when you flush the toilet the seemingly solid movement suddenly disintegrates into a brown cloud.
I took a shit that looked like it could choke a donkey but I realized when I flushed that it was just a Hokus Pookus.
Being productive whilst doing your business on the toilet. For example, replying to e-mails, reading up on the latest 'hot' news, stalking that girl you like on Facebook etc.