A feminist is someone who believes in the equality of the sexes (only referring to genitals, not genders); so no matter what parts you have, you should be treated kindly. I believe that everyone should be a feminist, however, if you are not, here are ways to not upset the feminist in your life.
1. Equality is key.
Feminists believe in equality. That means their partner should do half of the cleaning and half of the cooking, and both parties should also have equal say when it comes to decision making in the relationship. Making sure both parties feel heard in decision making is a key part of a healthy relationship, but a feminist definitely will not tolerate not being heard. In our society, men typically don't do housework, or even half of the cooking, because women are thought to be superior when it comes to domestic tasks. Sharing housework helps strengthen relationships and also keeps your partner from developing housewife syndrome.
2. Don't make sexist jokes.
Besides not being funny, sexist jokes make women uncomfortable and make a mockery out of feminists and what they fight for. Laughing at sexist jokes in front of your feminist partner, will most likely make them feel uncomfortable or like you don't value their opinions. There are other types of jokes to make without being offensive. If all of your comedy offends someone, are you a comedian or just a jerk?
3. Don't minimize their feelings.
Feminists are usually highly opinionated, and their controversial thoughts on women's rights may not be their only unpopular opinion. Instead of brushing off things they say to you, try actively listening and asking probing questions about why they feel the way they feel. Women have been brushed aside and not heard for such a long time, and you don't want to continue to do that. Understand what they are saying to you, and even if you don't agree, listen.
4. Normalize periods.
Periods are something that plague womankind, and while other people are often extremely grossed out by them, so is the person that's bleeding. When I'm on my period, I feel uncomfortable and the last thing I want is someone telling me that my period is inconveniencing them. So to keep yourself alive, and everyone happy, don't act like periods are gross. Act like it's natural, because they are.