(This will end up going way into graphic man-man sex territory, so it’s not for kids or the sexually modest.)
It started mildly enough, with an ADS-L posting yesterday by Joel Berson entitled
“pop”, noun, = ‘an ejaculation’ in 1722? As a verb, it dates from 1958
about the sexual slang verb pop ‘ejaculate’ (a natural metaphorical extension of explosive pop) and its nouning pop ‘an ejaculation’. The OED has the verb from 1958 on, but doesn’t have the noun at all, yet Berson found a 1722 quotation that might conceivably have an instance of the noun — though the text is far from straightforward in its interpretation.
According to the evidence in OED3 (Dec. 2006) and in GDoS, taken together, the verb seems to go back only to the mid-20th century, while the noun might go back as far as the mid-19th century (which would bring it much closer to Berson’s 18th-century text).
And then I have a vivid recollection of my first experience with the verb, which is what will take us into graphic mansex territory.