|"It's Du-Kay Johnny"|
|Season 5, Episode 22b|
|United States Airdate:||April 11, 2012|
It's Du-Kay Johnny is the second part of 89th episode and the 178th episode over all.
When Dukey's altered DNA begins to degrade, the Test sisters attempt to upgrade it, only to alter his personality in the process. Johnny must put up with his best friend's new outlooks on his life until the twins find out what went wrong.
Dukey is starting to behave too much like a regular dog due to genetic degradation, so Susan and Mary decide it's time for a DNA upgrade, but it turns him into a sophisticated dog named Du-kay who would rather spend time at a country club than hang out with Johnny. When he had another DNA upgrade he had the DNA of Hucklebarry Finn. When Johnny wanted Susan and Mary to have his old one back, the motherboard was fried.
Susan and Mary gave him a video calling watch that can also make him teleport. Meanwhile, Dukey was eating one of Hugh's meatloaf in Johnny's room. When they both had a conversation Dukey said he had to go back to a farm. Meanwhile, Dukey said that he liked watching the grass grow, but Johnny got bored and he wanted to do something dangerous and exiting so they went to a junk yard and they did a dangerous activity and Johnny was about to get hurt then Mary video called him through his watch saying that they fixed the motherboard and they're ready to go. When Johnny teleported Dukey and him back to the lab, Dukey got another DNA upgrade which changed him back to normal.
- Running Gag: Johnny getting jealous and disappointed of "Du-Kay".