We haven't done this in a while, so we're raising the stakes. Mangesh and I invited a special guest artist to draw on our whiteboard. Rather than just draw one element as we've done in the past, our guest artist drew three. To win a free mental_floss t-shirt, all you have to do is correctly guess one of the following subjects, which are all depicted in our guest artist's work:

1) A method of transportation
2) A non-profit organization
3) A five-letter word (Hint: in Scrabble, this word's tile value would be 11.)

4) Guess the mystery guest artist

Keep reading for the rules...

mental_floss_t-shirt.jpg1) This is a complete game of chance, the equivalent of us saying "We chose a number between 1 and 1,000,000. Guess." (More accurately, today we're saying "We picked several numbers between 1 and 1,000,000.")

2) You may guess four times, but all four guesses must be in separate comments. You can see a sample guess below.

3) Along with your wild guess, tell us which t-shirt you'd like if you win (browse our store).

4) Comments don't appear on the site until we moderate them. But we'll be able to tell who was the first successful guesser for each of the four possible correct answers.

That's far too much explanation for a crazy game of dumb luck. Get guessing.