I once had a woman bicycle into me on a somewhat narrow path, I thought she saw me and was turning but she didn't and ran right into me at a running pace.

I instinctively put out my arms to stop her, grabbed her shoulders and then realized she might fall over if I just did a brief push to stop her so I kind of lightly held her in place for a second until she stabilized herself.

It was the most harmless yet awkward accident I have ever been in.