I've hired at least a couple of people at semi-social occasions, ie over a pint, the last two IIRC being data scientists.

That was enjoyable for all parties I hope, and a bit weird: a mathematician/quant coworker that I hadn't seen for many years happened to be at the bar so I got him to improvise a couple of questions!

Honestly, I've never had an interview that I would have called "fun". Every single one of them was a stressful event that I had to suffer my way through. Some more stressful than others, but none more fun than a root canal. Even the ones where I already had the job and the interview was a formality.

The best interview I ever had, they handed me a small bug in their real codebase and we fixed it together. No whiteboard, no trick questions. It felt like a normal work day sitting next to a coworker, and that was a big reason I took the offer.

I try to do the same now when I interview people. Pick something that is actually broken, sit next to them, and see how we think through it together. You learn way more than you do from leetcode, and the person is not miserable the whole time.

One small thing that helps a lot: tell them up front it is fine to google stuff and ask me questions. Takes the pressure off, and it is a lot closer to how the job really works.