Jimmy's very well-proportioned miniature
While making his miniature, Jimmy becomes fixated on getting the proportions correct, and so starts measuring the parts of his own body in relation to the size of his head.
To get the width of his shoulders correct, he asks Tom Cashman to help measure it, using the width of his head as the unit, and Tom states that he is "three JHs wide".
Tom then also helps him measure other parts of his body in 'JH's, a measurement which can apparently be used to refer to either the height or width of his head.
Jimmy then realises that he needs to figure out how big to make his miniature's eyes, and so sets about measuring how tall his head is, in comparison to his eye.
It seems like he perhaps uses most of his time measuring, and is then left with very little time to actually build his miniature, which he makes out of coloured modelling clay, and gives some of his own hair.
He poses it in a miniature shopping trolley, noting that the figure is not actually in proportion to that item.
In the studio, after explaining what a 'JH' is, Jimmy warns Tom Gleeson "Don't ask me what a JC is", thus coining the title of the episode (presumably, a 'JC' would be a 'Jimmy's cock').
Tom awards Jimmy third place.
(Written by Karl Craven)
(Illustrations collected and adjusted by: David Fuller)