Welcome to the Spam Hall Dilemma.

Only one of these cans contains Spam.  Choose a can.  After your choice, we will reveal an empty can.  You will get a chance to change your guess, if you choose.  Click a picture below to start:

Based on the Monty Hall Dilemma

The explanation: The spam has a 1 in 3 chance of being in any given can. When you choose one, the spam has a 2 in 3 chance of being in one of the two cans you didn't pick. Seeing an empty can changes nothing about those odds. The spam STILL has a 1 in 3 chance of being in the can you picked and a 2 in 3 chance of being in one of the other 2. Except it's not in the empty can, so it has a 2 in 3 chance of being in the can you didn't pick. In essance, you are picking BOTH of the other cans by switching your guess.