English physician Samuel Farr was pretty certain women couldn't get pregnant without an orgasm. The Guardian quotes the mansplanation from his 1814 Elements of Medical Jurisprudence: "For without an excitation of lust, or the enjoyment of pleasure in the venereal act, no conception can probably take place. So that if an absolute rape were to be perpetrated, it is not likely she would become pregnant."
According to Hart’s 'mansplanation,' the STFU Ladies holiday is celebrated by the unification of men everywhere to “enjoy the ‘fruits’ of what [they] call football on this glorious day.”
2012 October 5, Harriet Walker, “Now, let me explain something about patriarchy”, in The Independent[1], →ISSN, retrieved 2012-10-05:
The mansplainer is often shocked and hurt when their mansplanation is not taken as absolute fact.
And now, at long last, there is a word for that kind of condescending, clueless explication: mansplaining, seen in the wild since 2008 and apparently first used in a web comment thread, but leaping up in popularity thanks to certain mansplanations during the recent election cycle — and to being Word of the Day on Urban Dictionary on February 24, 2011.
2014 October 16, Micaela Beltran, "Under the Covers", The Georgetown Voice (Georgetown University), Volume 47, Issue 7, 16 October 2014, page 10:
This phenomenon depicts a man explaining something to a woman from a “more knowledgeable” standpoint, though such mansplanations are always about things which the woman understands more fully.
2014 October 28, Alex Marwood, The Killer Next Door, Penguin (2014), →ISBN, unnumbered page:
Vesta's left me alone with him so he can give me some sort of Big Daddy lecture. Because the thing I need right now is a mansplanation of the error of my thinking.
Noun: "(uncountable, informal, sarcastic) the act of mansplaining"