40 of the most obscure rules Olympians must follow

Competitors in the boxing competition must be clean shaven or have limited facial hair. That pencil mustache is a-go.

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.

While gymnasts can wear colourful makeup, bright nail polish is a no-go. It's either neutral or none at all for these athletes.

Athletes are not allowed to express any form of protest on the field of play, in the Village, during ceremonies, or at the opening and closing ceremonies. The rule was put into place prior to the 2020 competition and has faced significant pushback.

When it comes to endorsements, athletes can have them and get paid for them. However, during the games, the athlete can't mention them, and the company can't promote the athlete either.

While you may think male figure skaters could wear tight a la dancers, that's not the case. Trousers are a dress code requirement.

While men have to wear pants, ladies aren't allowed. Even if they're simple and sheer, a skirt is required.

Per the International Olympic Committee, drinking is allowed. Athletes can even bring in their own alcohol to the Village. However, some athletes have no drinking rules imposed by their country. For the USA's athletes there's no booze in the Village but outside, it's fair game.

While athletes can use and post to social media during the games, there are restrictions. Images and video showing the field of play or backstage areas like athlete and coach only ares are off limits.

BMX athletes are required to tuck in their shirts — even if it is to matching pants.

While fights are rare in Olympic hockey, athletes don't want to start one, but they may want to finish it. While instigators get five minutes in the penalty box, those who drop the gloves second only get two.

Dunking is allowed in Olympic basketball. However, players aren't allowed to hang onto the hoop after doing so.

If a swimmer sets a world record, it's not automatically recorded. Athletes have to fax in their record. Yes, fax.

This may not seem odd, but it is. If a challenge or appeal is wanted during a match, the athlete cannot leave the piste or field or play. In 2012 South Korea challenged a call, and fencer Shin A-lam was forced to stay on the piste for nearly an hour before a decision was made.

Olympic wrestlers have to cary a hanky somewhere in their uniform called a "bloodrag." Yes, it is used to clean up any bleeding from competition.

To avoid chafing, swimmers can grease their elbows and inner thighs, but they can't use too much.

Water polo athletes have to clip their toenails in order to avoid some nasty scratches under water.

There's no smoking throughout most of the Olympic Village, but there are designated areas for those who choose to do so.

An apple? Yes. An apple and a to-go tray? Not so much. Only one hand-held item or one beverage can be removed from the Olympic Village food court.