Briefly: there was no such day - unless you are talking about the days before Obama was known to be in line for power. Not just us, but the spreaders of that poster. So what was the attraction, the viral push, of an image that doesn't fit on its admitted grounds? Not just a little bit no fit, but a dramatic and obvious mismatch? There are a very large number of mismatches and nonsense comparisons available - a telling caricature is a difficult creation, because it was produced from such a large number of possibilities. Hence the revealing nature of correlated falsehoods and errors - the statistical power of the correlation is very high. The number of wrong-headed caricatures available for selection is huge. It's as if the punchline of a joke didn't have to be either funny or relevant to the rest of it - suddenly a very large selection of phrases will work for you. And of those thousands, the chosen one is racially loaded.