I mention that Thucydides believed that the stronger a nations military was, the weaker its democracy is and then talk about how "even a Republican like Eisenhower" made the same point when he warned us about the military-industrial-complex.

This primes them, it pitches their liberal values against the military and primes them to hear whatever Noam Chomsky argument I'm about to bring up.

Plus it's fun watching them pretend to know who Thucydides was, since being the smartest dude in the room is as central to the liberal worldview as any actual values are.