A laugh from an NT doesn't necessarily indicate that they think you're joking. A laugh can mean approval of your forthright nature, surprise that you actually said what everybody was thinking, or surprise that you were thinking about something in a way that is novel and pleasant to them. Of course, deadpan statement of unexpected facts in and of itself is a form of humor, so some of those laughs are just going to be appreciative that you expressed an idea in a fun way.