I was on a cross-country flight today, only half-paying attention to the passenger instructions, when I heard the flight attendant say, "..and please do not conjugate in front of the restrooms!" I'm sure she meant congregate, and it's quite possible that I heard her incorrectly. Perhaps I have a dirty mind, or perhaps it was just the association with airplane bathrooms and what's said to go on there, but I found myself chuckling at the idea of two people doing the deed in front of the bathrooms.
It occurred to me later, though, that I don't think I've ever actually heard the word conjugate used in reference to sex, though the phrase "conjugal relations" is certainly well known and often used. From Latin, con + iugare means simply "to join together". The more commonly used word is copulate, from copula, link. I tried Googling conjugate to see if I could find an instance in which it has the meaning I ascribed to it, but the word has too many uses in biology and mathematics for that to be a useful exercise.
Anyway, I don't think they'd want people standing in the aisles reciting Spanish verb forms either.