Mantyhose. They are a real thing. And, exactly what you might think they are - pantyhose for men.
Now, men wearing tights isn't really a new thing. Think back to the days of King Henry VIII, dudes wore tights all of the time back then. In fact, you were probably looked at funny if you didn't wear tights. But, at some point, it was decided that tights and pantyhose were a female thing, and the trend of men wearing them dwindled. Until now.