The teenaged son thought it would be better to try to smoke the weed in his sister's room, because of the cross-ventilation. No one would smell anything. They were all out at the movies anyway - Mom, Dad, the twins. Some stupid Christmas movie.
Turns out when both windows are open and the wind is coming from the northwest it blows the smoke inside
He opened every window in the house but he swore he could still smell the smoke oh man they'll be home any minute and they'll know everything
When they did get home he was wearing a sweater and he said the heater wasn't working. Dad frowned at said he'd go downstairs and check.
When Dad came back he said sure enough, pilot light was out. Mom said well I hope you fixed it and Dad said sure did. Dad gave him a long, long look, then left the room. It was the next day before he remembered the house was all electric.