Twelve:
Hilarious antics were ultimately not what forced Brian's parents to confront the clowns waiting at home for them. They agreed to not call the police, and allow themselves to be taken hostage, if the clowns agreed to not kill each other. They told Brian to wait at the Bannisters' for them.
"What if you don't return?" said Brian.
"Then I guess your Aunt Kelly can take you in," said Brian's father.
"Yes," said Brian's mother. "Pray we return."