If I'm not as talented as Viv Stanshall does that mean I'm sub-Stanshall?
It is a joke you see. Sub-Stanshall is a homonym of substantial. I made it up myself.
Prodnose: Are you the front end of an ass?
Prodnose: Are you the back end of an ass?
Myself: I'm not.
Prodnose: Then you are no end of an ass.