Expunctis:

Let’s play a game. You press ← and → as randomly as you can, and I will try to guess your next input. Use your keyboard or the buttons on touchscreen devices.

Every time I guess right, I will take $1 from your virtual account. Every time I guess wrong, you’ll get $1.05. If you are as random as you think, you’ll be making virtual dough in no time. Don’t worry, there is no cheating involved. I simply keep track of the patterns you produce and use them to predict your next move.

This is weirdly fascinating.