The One-Bounce Rule
This next rule sounds like something your mom forced you to do when your six-year-old nephew wanted to join the big kids' kickball game. Incredibly, all the way until 1864, fielders were allowed to "catch" a player out on one bounce. Yup, you could either attempt to catch the ball on the fly, or wait for it to take a slower and safer hop. Both counted as an out, and one-hop fielders weren't even laughed out of the league.
The reason for the one-bounce rule was that the baseball glove had yet to be invented. The very first gloves were slowly adopted by catchers in the 1880s, and the first "pillow-type" catcher's mitt wasn't invented until 1888. The first mention of gloves in the official rule book didn't come until 1895. If you've never caught a line drive with your bare hand, you're in good company. Nobody does it because it's really dangerous. You could break digits or even your wrist. In the utter absence of gloves, the one-hop rule looks a lot less wimpy.
Even after the one-bounce was abolished for fair balls, fielders were still allowed to catch foul balls on a bounce all the way until 1882 in the National League and 1885 in the American League [source: Nemec].