If a girl was to have a train run on her with no protection....

Your much more likely to catch a pregnancy if you climax with a fresh load.

Let's say first guy finsihes but you don't.
Second guy starts. First one spills out a bit. The penis has a mushroom head to scrape out the seed of other males BTW. Second one finishes in you but you cum with him. Way higher chance #2 wins that pool. The egg is first cum first served.

There was a way to be less dismissive and simply talk about "multiple partners" instead of using a misogynistic expression.

Viability of sperm is such a high factor in what reaches the egg first that I can't see order mattering.

If we're talking a full day of cream pies, yeah, the guy that goes last isn't going to have his swimmers even medal, much less take gold.

But an hour? Nah, not a big factor compared to sperm motility.

Mind you, there would be an advantage to going first, it just isn't going to be a huge factor compared to motility and sperm health. If number one has a low count and poor sperm health, number fifty would have a better chance if theirs are Michael Phelps in sperm form.

Mind you, if the ovum is there and ready, the journey to it isn't going to take hours and hours, so the bit about number fifty is an exaggeration for funsies. That would only be realistic if they were all premature ejaculators and moving fast.

However, sperm health still matters in that hour longish window. It the first guy has bad sperm, and/or a low count, the guy going last could still end up being baby daddy instead of him.

Out of the millions of spermatzoa that are in a healthy jizz, you might have a few hundred that actually make it to the egg's location, and there's still a chance that the first one to touch the egg isn't the one that succeeds. It isn't like they tap the wall, and it's over. There's some chemical magic involved that doesn't trigger immediately on contact. So, if sperm 5 is perfect, and sperm 1 isn't, #5 could trigger the event that makes the others not be able to wiggle their way in.

Believe it or not, gang bangs to get pregnant are actually a thing. It isn't always the first guy that ends up with a biological child.

I red sometime that the penis is shaped like it is to extract the sperm of the previous delivery. But anyhow I believe it is mostly random which sperm willmbe received by the egg.

Usually, it's first cum, first served

There is a good number of factors going into it to be easy to determine: sperm motility, count, quality and quality of the seminal fluid, cervical mucus acidity and fluidity and chemical compatibility between the two are a few.

Then there is the sperm competition, as sperm cells of different donors compete between each other.

And then there is the mechanical action of penetration, that, considering how apt the penis is to perform the action, pulls out as much as there is inside possible.

Oh, and the more prolonged/frequent intercourse is, it may contribute to lower ph vaginal levels, which is not good for sperm life expectancy.

It boils down to evolutionary competition.

But one last thought: run a train? There are less judgmental ways to say the exact same thing.

You could try this out and see who wins? Report back with results

Probably the first guy, but sure, yeah, if he's got poor sperm then it would probably the first guy who doesn't.

It's usually the 2nd or third sperm to reach the egg that penetrates, but each ejaculation carries millions.