When it comes to conduct on and off the field, there are Olympic rules athletes have to follow, and some are next level obscure.
Shoes: While shoes are almost always worn by athletes competing in track and field events, they're not required. But there are rules about the shoes.
Nail Varnish: While gymnasts can wear colourful makeup, bright nail polish is a no-go. It's either neutral or none at all for these athletes.
Toe Nails: Water polo athletes have to clip their toenails in order to avoid some nasty scratches under water. Furthermore, they are not allowed to oil up before matches.
Socks: When it comes to Olympic cycling, there's also a strange uniform rule. Socks can't be higher than mid-calf.
Spromotion: Athletes can have endorsements and get paid for them, but during the Games athletes are limited to one message for each personal sponsor per event; one message per sponsor on any one day; three messages per sponsor throughout the Games; and a maximum of ten 'thank you' messages per athlete throughout the Games period.
Skaters: Men must wear trousers whilst women can wear a variety of costumes including trousers, leggings, skirts, dresses, and unitards. Clothing for female figure skaters 'cannot give the effect of excessive nudity'. That's exactly why you see so flesh-toned panels - to give the illusion of skin without breaking rules.
Basketball: Dunking is allowed but players aren't allowed to hang onto the hoop after doing so.
Rhythmic Gymnastics: Throw that hoop or ribbon too high in rhythmic gymnastics, and that's too bad. Props can't be retrieved during a routine, and athletes must keep going without them - even if their hoop is in a rafter.
Pay to Challenge: If a team believes a score is unfair, gymnasts' coaches have four minutes and must pay $300 to have it re-evaluated. If the challenge overturns scoring, the team gets their money back. If it's not, the cash goes to charity.
Wrestlers: Olympic wrestlers have to wear a cloth handkerchief somewhere in their uniform called a 'bleeder' or 'bloodrag'. Yes, it is used to clean up any bleeding from competition or to mop the mat of any bodily fluids.
Beach Volleyball: If teams show up in the same colour, a coin toss gets to decide who has to change.