What is "Stud Racing"?

I've seen this term used a few times, but I have no idea what it is. What does Stud Racing mean?

Not sure if it's even possible here on WD (I imagine they implemented what they did on LD from the get go to stop it), but basically it was a thing on LD where you sent a stud request to several studs, often with 1% fert girls, and sometimes people made it a competition even (like the one who gets the female pregnant finally gets a bonus + the stud fee). It was kind of a mess.

Yeah,  it's not possible to do it here on wolvden (I've accidentally tried to send out a stud request for a girl I'd forgotten already had one out). You'll get an error message if you try. Some people use it to basically mean 'don't cancel your stud request too quickly, give me a chance to get to it', but you can't actually 'stud race'.