It's a slippery slope. You send an instant message to a work friend to "vent" about a coworker. They commiserate. Before you know it, it's a full-on bitch session or worse. It feels good in the moment to get it off your chest, but do it a few more times and it becomes normal and then other stuff creeps in. The NSFW jokes. And, probably, from there, inappropriate pictures. I never did more than gripe, myself, but when my closest work friend retired, I stopped and I'm so grateful for the passage of time and a retention policy that purges everything after two years.