Faux Chapeau is the second part of the 4th Aired and 3rd produced episode of season 4, which first aired on May 9, 2003. In this episode, Dexter's invention becomes a great bestseller, but the invention later causes people to have enlarged heads.
The episode name is French and it roughly translates to "False Hat."
After hard working in the lab, Dexter went outside to find some drinks. Only found out Dee Dee was selling his invention to people when he got back. Dee Dee then persuades Dexter the idea of selling them as hats. Since then, the hat business took off, and it’s getting bigger and bigger until eventually forming a large corporation. After a while, they found out the problem cause by this invention: since this invention is meant to magnify molecules, put it on people’s head will also made their head huge. Luckily, an ointment can help their customer’s head back to normal size, so he duplicate 50 million tube of ointment, and refund to the customers. After the refund was completed, Dee Dee told Dexter she has sold Dexter’s another invention that looks like shoes.