Is it OK for a male and female friend to sleep and shower together?

Better be a pretty solid friendship - at least in America.

If they're both okay with it and it's not hurting anyone else then it shouldn't be a problem.

Better not to, even if you're married. People reject the old-fashioned practice of spouses sleeping in separate beds, but it is a good idea. The more mystery and longing you maintain in a relationship, the longer the attraction will last. If you burn through every imaginable form of sexual interaction, you will get bored with each other.

Sexual attraction and the relationship energy that comes with it are more about what you don't do than what you do. The more you don't do, the more untapped potential you have to energize your relationship.

For some period of time, fraternal twins slept and showered together.

Sleep and shower at the same time? Well, that certainly saves time and they wake up fresh and clean. Seems like a good idea. Doesn't matter what genders they are.

Back in the days when I was growing up, it was fairly common for what was known as "friends with benefits". Yes, it took a very strong friendship if the desire for both involved was to remain nothing more than friends with a little something on the side. I had a few friends with whom I had either one time flings, or with some, occasional to frequent "benefits"...

It is absolutely OK for two consenting adults to sleep and shower together.

It is not clear whether "sleeping together" in this context implies that they are having sex. As a heterosexual male, I would find it very difficult to sleep or shower with a woman that I wasn't having sex with. I would certainly consider sharing a bed or showering with a woman to be foreplay, and I would want actual sex.

There nothing wrong with casual sex (or any time of casual sexual activity) between adults as long as both sides want and enjoy it. In my personal experience, these "friends with benefits" things, are far less gratifying that I want and I end up either getting bored quickly, or my feelings escalate.

I enjoy showering with a sexual partner. It is fun, and sexy. It is definitely part of a sexual relationship. I can't imagine showering with a female friend that I wasn't in a sexual relationship with.

Can we have more details?

its ok if there have no objection.