Big Brother has been very excited about molecules since making them with marshmallows last week. He's been playing with the PhET simulations and discovering new molecules. Today he was playing on PhET and came running down to ask if he could have one large and four small marshmallows because he'd discovered a new molecule he wanted to build. He duly made it, then took it to Little Sister and offered it to her. She ate it and he cracked up laughing.
"You just ate a FART... that was methane"