Season 3

Jimmy inserts a smart chip into his pants but his pants develop a mind of their own and before long an army of pants is threatening the citizens of Retroville.

Being smart can be hard on a guy. So Jimmy invents a machine that reduces his awesome brainpower./Jimmy uses his brain power to beat Cindy in a candy-selling contest.

In his lab, Jimmy constructs the perfect little brother he never had, "Brobot". But trouble brews when Brobot is both more popular than his creator and very annoying! / To settle a classroom argument with Cindy about who really invented radio, Jimmy brings Thomas Edison to the present using his Time Pincher. But the future of western civilization is subsequently threatened when Edison takes a shine to Miss Fowl and refuses to return to his own time!

Jimmy's Granny comes to stay while Judy and Hugh are off on a third honeymoon.  Jimmy, concerned by her ailing health, gives her his new youth tonic.  However, the potion works too well - Granny ends up as a talking baby! Through the wonder of time travel, Jimmy goes 15 years into the past to a time when his parents were swinging sweethearts.  Jimmy's investment tip changes the future so that the Neutrons become fabulously rich - but with unintended consequences!

Jimmy invents the DreamInjector 5000 and enters Carl's dream to figure out what his friend is afraid of. / Jimmy and Cindy have to collaborate on a science project.

Jimmy's attempt to cool off the summer heatwave in Retroville has the unexpected result of plunging the city into a new Ice Age. / Jimmy, Carl and Sheen form a band in order to beat out Cindy and Libby for the school talent contest first prize. With Jimmy's souped-up instruments, the band sounds amazing. But egos swell out of control, and the ensuing bickering between the band-members almost destroys their friendship.