I've seen a few so far.
The first one involved a Legion soldier getting chased through the desert by 6 or so NCR troopers. The Legion soldier literally ran into a rock and stood there with the top half of his body completely visible while the NCR soldiers all circled the rock saying things like "You can't hide forever" and "I'm going to find you". All of these guys were bugged in that I couldn't interact with any of them, and the legion soldier conned friendly to me, even though I'm vilified to legion troops.

The second one I saw was a Ghoul roamer that resurrected himself and came after me again after I killed him.

Share your funny bug stories!

I guess this is kinda funny, but I was in the Vikki and Vance Casio, checking out the "death car"
Somehow, I got too close and wound up inside the car. (remember the old Daggerfall days getting stuck in walls and floors? Well it was like that) So I tried jumping to get out of it and I accidentally fired my pistol at someone and hit them. Everyone started shooting and soon I was dead.