I was never in theatre, but my best friends were. So many stories.
One friend was really big into community theatre. I would expect non-professional theatre to be more modest--separate changing areas, etc--but nope, he got to enjoy a lot of sights. Wardrobe malfunctions almost every night they were in production, etc. Although the stories of cast members not wanting to kiss each other were far more enjoyable to hear.
I had a close relative hired for a musical bit in a professional theatre. She had no theatre experiences at all. She was paranoid about everyone changing together. She would wear everything to the theatre and didn't have a costume change. But one night she was coming from somewhere else and had to get dressed with the cast. She had to get at least topless to put her costume on, and she said she enjoyed being topless in front of other topless women and men in tight undies as she described it, so she finished the run by getting dressed there. I guess it's more of a emotional wardrobe malfunction on her part.
Another friend of mine became a director of theatre at a college. Everyone asks him to tell us stories, but he doesn't really want to. But he did tell us one: Walked back stage because things were going well and he heard commotion during intermission. He found his lead completely buck naked head to toe, which he was confused about because she didn't have costume changes that required her to get naked. Well, apparently someone fixed a customer after the previous night's run, and they left in sewing pins that were scraping her skin. So, in a panic, she got COMPLETELY naked so people could help her figure out what was going on (they didn't know it was sewing pins yet at that moment, so she just took everything off). He said her lack of embarrassment of him seeing her made HIM embarrassed.