A puzzle recently posted at 3 Quarks Daily will make you think. Or at least it should make you think.
There are two boxes on a table, one red and one green. One contains a treasure. The red box is labelled “exactly one of the labels is true”. The green box is labelled “the treasure is in this box.”
Can you figure out which box contains the treasure?
Now, before you decide that you know, pay attention to how the question is asked. The answer and an explanation is at The Universe of Discourse. The author also addresses the many ways you could ague that you are right, even if you aren't. -via Nag on the Lake