Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3)
Me: Are we alone in the universe?
Siri: No comment
(or she usually says "I cant really say")
That is not necessarily an easter egg. Ask it a bunch of other questions and you'll find that 'no comment' is somewhat of a standard response.