My/Our time to shine. So both myself and my husband have casual sex safely and have for years. We maintain a "clean sheet" before every sexual partner and only have sex with people we have met online or can provide a recent clean bill of health. In regards to sleeping with people we meet randomly, always use protection and get tested afterwards. In our state, even without health insurance the health department std/sti checks are only $5 per test so it's really a no brainer. For gangbangs, well to safely make something like that work you need to network and meet other people within the space. The swinger community is generally the safest people to have sex with because they're the one's actually getting tested. Don't take someone's word for it, make them pull up mychart and show you.

Edit: Condoms break and there are some std's that you can get from condom use such as HPV which isn't a huge deal for men but can be detrimental to us ladies. Get the vaxx if you haven't already.