I'm reminded of a joke I heard a long time ago (copy/pasted from elsewhere online)
The American Government funded a study to see why the head of a man's Penis was larger than the shaft. After 1 year, and $180,000, they concluded that the reason that the head was larger than the shaft was to give the man more pleasure during sex.
After the US published the study, the French decided to do their own study. After $250,000 and 3 years of research, they concluded that the reason the head was larger than the shaft was to give the woman more pleasure during sex.
The Irish, unsatisfied with those findings, conducted their own study. After 2 weeks, a cost of around $75.34, and many pints of beer, they concluded that it was to keep a man's hand from flying off and hitting himself in the face.
lmao, this is a theory, and this study hasn't only not been peer-reviewed, it doesn't seem to have gained much of any traction in the academic community in the last 20 years.
if I paid 600 college students to fuck each other, yeah, I'm going to find that one penis is going to squish out the cum from the last penis, but that doesn't prove that it evolved specifically for that purpose. isn't simple displacement, and a task that could be as easily performed by a dildo or fist or anything else that you shoved into the jizz-filled cavity.