Drawing Gas

My mom and Aidyn were playing a game where they would draw on each other's back and then try to guess what was being drawn. At one point Aidyn was drawing and my mom was guessing. "A car?" she guessed, and Aidyn said, "Nope, but it does have gas." Finally after many other incorrect guesses Aidyn declared that she was indeed drawing gas. Come on, mom...how could you not figure that out?!