It's amazing how often people confuse the "things weigh nothing in space" thing. Sure, in space and not in a gravitational body I would "weigh nothing" and a 2 year old could, theoretically, pick me up. Say if we were on a very light object with no meaningful gravity (like an asteroid.) But weight and mass are different things.
If you want to puncture that misconception,just remind them that the Earth is in space, too. Does it weigh nothing?