Humorous descriptions are often couched in the form of a simile, whose flexible frame allows an author to yoke a topic to a perspective that is at once both incongruously different yet appropriately similar. Humorous similes exhibit all the commonly accepted hallmarks of verbal humour, from linguistic ambiguity to expectation violation and appropriate incongruity. But so too do non-humorous poetic similes, which exhibit an equal tendency for the ingenious and the incongruous. What then separates humorous similes from the broader class of creative similes, and can their signature characteristics, if any, be expressed via the presence or absence of specific formal, structural or semantic features? To address these questions, we describe the construction of a very large database of creative similes, and present the results of an initial empirical analysis upon this data-set. Our results are two-fold: humorous similes exhibit many of the same structural and semantic features that are considered characteristic of poetic similes, though none appears either necessary or sufficient to make a simile not just creative, but humorously creative; nonetheless, similes that employ either irony or ridicule (or both) are often explicitly marked with a marker of semantic imprecision such as “about”. We go on to show that “about”-marked similes typically exhibit an identifiable affective signature that further telegraphs an author’s humorous intent to the intended audience of the simile.