I can't locate the reference, but I've read, and observed, that if you want to verify that the person w/ whom you're conversing is paying attention to you, cross your arms: if the other person crosses their arms also, then they're paying attention to you.
Oh God, I can see it now, startup pickup artistry:
"Yeah, I negged that investor twice and then escalated kino, and then popped the termsheet. You're a beginner--try a cold-open with a Paul Graham story and look for indicators of interest."
