How do you get that rare status bar face?

So I made some type of arena map that was just spam of Imps and zombies and I keep getting that weird face and I think it is caused by me getting hit like half a million times,what actually triggers it?

https://doomwiki.org/wiki/Ouch_face

"Rarely" It happens in like 20 seconds for me in my map,maybe because i'm again getting shot every 1.5 seconds.

Lots of source ports have "fixed" the bug so now you make the face every time you get hit for more than, like, 20 points of damage.

You have to simultaneously take damage and pick up a health bonus. See this video for an example.

Starting a level in a damaging sector will do it as well.