When he is talking about increasing the pressure in a system and uses inflating a bicycle tire as a real-life example, and then says there aren't a lot of everyday examples of decreasing pressure, you might say something about suctioning a drinking glass onto your face.
I do that every day, doesn't everyone?
Or, while asking him a question during the procedure, you notice he is wearing a shirt that has the same college as your former roommate. You ask if he attended there, which year? When he says 2011, a good idea is to say loud enough for many people to hear "What?! From undergrad???" as you realize/try to make sense of the fact that OMG when I graduated college, this guy was still in high school!