Actually, the first night privileges are largely, if not wholely, a myth.
http://en.wikipedia.org/wiki/Droit_de_seigneur
Droit de seigneur - “the lord’s right”, often conflated with the Latin phrase “Jus primae noctis”), is a term now popularly used to describe an alleged legal right allowing the lord of an estate to take the virginity of his serf’s maiden daughters. Little or no historical evidence has been unearthed from the Middle Ages to support the idea that it ever actually existed.
I’ve read a small amount (compared to actual scholars etc) of contemporaneous medieval documents in books and have never even seen that mentioned.
OK, BUT, could the Lord not have any privileges he wanted with the serf girls? Who was to stop him.
Other than the fact that this supposed custom predates the 16th century and the vulgar street term can be traced to the early part of that century, there is no evidence to support either urban legend. That does not necessarily mean that they are false, just no evidence that they are true.