Not last night, rather last month. This place is out in the country up towards Mt. Hood in Oregon, about a twenty minute drive from where I live in Washington State. It serves an old nine hole golf course and when the weather's nice there will usually be at least 40-50 civilians and 10-20 musicians. The host plays mandolin and guitar and is conversant in many styles, so many players choose to use him for backup. Most of the open mics I frequent feature a lot of working pros, many of whom I've known for 20-30 years or more. I tend to sign up for a three song slot and then wait and see who gets shut out of the 10-12 15 minute sets, then grab a few and work out something to play. I also do solo bass sets with vocals sometimes though, or jazz duos with the host where we throw darts at his iPad and wing a few Real Book tunes. I subbed in one of his gypsy/swing/country bands years ago, and still have their book, so I can shed on a few tunes beforehand if the mood strikes too.
And then for the last hour we typically turn off the PA, circle the wagons, and go around the room with everyone getting a couple of features and a lot of learning going on. I am allowed to plug in my bass, and really weak singers might get a mic if the host deems it necessary, but it's all acoustic beyond that, and often sublime. Some folks just show up for that last hour, and the staff take a load off and relax a bit, while starting to clean up a bit. We quit around 9PM, which is official closing time.
This is the view of Mt Hood from the parking lot:
And then this was the last electric set, which I got pulled up for with no notice, just after I finished a set with a singer-songwriter I'd never played with before:
I don't own a fretted bass, but I had just finished a preamp install on that one and wanted to see how it sounded in a full mix. No advance notice of the song selection, but at least it was something I had heard 40 years ago...