Alternate title is "Stocking Stuffers," but that kinda gives the gag away... at least I know from firsthand experience how much fun it's been watching folks figure it out. The delayed realization kicks in after the eye is led first from the panel's entry point with the eyes (gaze direction in compositional arrangement); steps leading down to the bear figure continuing the movement into the panel > foreground element of spilt milk + bright contrasting white > sweeping rug tracks up to the upswung pointers of the fireplace rack (also a framing block with the spot black spruce tree) > that in turn leads to the core of the panel and the payoff gag (literally for some) with the stockings.
A little bit of color theory too what with the brighter points working to aid eye-flow across a cluttered composition and some contrast (ex: green/red, which helps explain the no-no of burning green wood). Lots of other incidentals scattered about the panel, which was used a penciling demo in the classroom and then as an inking demo for a public appearance: a really fun one to draw, and now graces this year's xmas card.
Again, the best part of all the whole process has been watching live as people decipher the panel... it's usually along the lines of "Oh! How cute..." followed shortly by "... eeewww" (or something to that effect). I get that a lot though.
A Very Happy & Safe Holidays from all of us here at Ink & Snow!