Heres something i did and which also maybe could be a good start for you there haha ;P
I put a match stick inside my uretha (only as deep as it needed to stay in) and then lit it up
I wanted to see how close i can let the fire crawl down until my reflexes snapped it away (on the video it seems like the flame already slightly touched my dickhead)
It was a very short pain but intense
SO i dare you to do it by yourself ;P
If you dont like uretha you also could use a longer match stick or a longer wooden stick and just put in in your pussy and see how far you dare to let the flame come down.... but pls watch out to not just let it burn your pussy it would be very painful for a long time i guess and could be harmful so you shouldnt let it burn down completely haha ;P
I hope you can understand what im trying to tell you ♥