Father Knows Least is the third part of the 6th episode in season 4 of Dexter's Laboratory, which first aired on May 23, 2003. In this episode, Dad is left in the care of Dexter and Dee Dee while Mom goes to visit her sister.
Mom is preparing to head out for the night, and she leaves Dad in charge of the house while she's out. After leaving, Dad continues to read the comics section of the newspaper, and forgets to do the first thing, which is to make breakfast for the kids. Due to Dad's inability to make breakfast, he offers the kids lunch money. Dexter comes up with a plan to make Dad give him and Dee Dee more money. Dee Dee outsmarts her brother by getting more money. Dee Dee heads out to school while Dexter pleads to Dad to give him more money. Dad sends Dexter off to school.
Dad goes on to do the dishes, but instead makes a bigger mess. He throws clean dishes into a dishwasher and puts the box of soap in there. He jams the dishwasher shut and turns it on. Dad then went to do the laundry. He puts in Dee Dee's dresses and Dexter's lab coats. Dad then goes to dust the mantel in the family room, but without looking, he knocks over several things while watching a Spanish soap opera. The doorbell rings and Dad meets a man named Chad who was looking for Mom. Dad doesn't buy what Chad says, and slams the door in his face.
Later, Dad vacuums Dexter's bedroom and puts in the Math 4 Fun book in the bookcase, revealing the secret entrance to Dexter's laboratory. Dad thinks Mom ordered him to clean the lab, but he leaves. Dad goes to get the dishes, but he does not realize that the kitchen is filled with soap bubbles. He goes to get the laundry and sees that Dexter's lab coats are pink due to them being mixed with Dee Dee's dresses. Dad then goes to make dinner, but ends up with a burnt spot in a square pan. Dee Dee and Dexter watch as the pan lets out smoke to their dismay. Dee Dee forewarns Dad about the living room being overrun with suds while Dexter complains about his lab coat being pink. Dad realizes that he's the worst housesitter ever and cries to his disappointment.
With time running out, Dad cleans the house as quick as he can. Later that night, Mom comes home to find the house unscathed. She runs over to Dad and kisses him as a reward. However, the happy time comes to an abrupt end when a maid tells Dad that she needs her payment. Dad gives her the money and sends her away. Mom is now furious at what Dad did. Dee Dee and Dexter reluctantly join in. Dad stammers and hangs a sign that says "OUT OF ORDER" around his neck.
This is the last episode when Dexter's Dad tried to clean the house making disasters in the previous episode "Another Dad Cartoon".