Where does the term fortnight come from?

Oh, dude, the term "fortnight" comes from Old English, back in the day when people wore tights and said things like "prithee" and "forsooth." It's a mashup of "fortnighten," which means fourteen nights, or two weeks in normal people speak. So, next time someone asks you to hang out in a fortnight, just remember you've got two weeks to come up with a solid excuse.