Adding on to Morgrim's solution: Bureaucrat and Cutpurse will also do to get a look at their hand. Or you've just been keeping careful track of their deck.
A more convoluted solution: You are playing a 3-player game where the scores are
You (1st player): 100
Alice, to your left: 0
Bob, to your right: 100
or, you know, something like that. There are two piles empty, including Estates, and one Curse left. You play the Militia, hoping to see that Alice has a Moat and, ideally, that Bob doesn't, so you don't accidentally give the last curse to Alice and lose on turns.