Oh how I do so loves me a good, punny caption disguised as a title. This one works on a couple levels, and is by extension in the lineage of the classic "The Humble Beaver."
It took a an unusual amount of preliminary sketching in conjunction with photo reference, which since nothing existing in reality corresponded with my mental picture, I wound up making up the architecture anyways. Structural impossibility to be sure, but it works as far as triggering an association. Some folks might have to hunt around for a few seconds to see the gag buried amidst the environment, but I think with linear perspective in conjunction with value + contrast the eyes eventually wander upstream.
I also indulged in a wider array of inking implements for this particular panel, in part on account of varying the line weights so as to imply or enhance pictorial depth in the composition of the panel. Also employed a variety of Microns for judiciously applied textural effects - not too much seeing as how the dimensions of the original was approximately 11x13" and regardless of how impressive it looks (and serve as a sort of stippling stress relief), at some certain point one has to say dam it all and move on.