In full contact sports like MMA anything can happen and yes that includes losing control of your bowel movements.
This is exactly happened to straw weight UFC Fighter Justine Kish (6W-1L) who fought Felice Herrig last UFC Fight Night: OKC.
If this happened to other people most would probably wish they can disappear, Kish however tackled this sh*tty event in the most bad ass way. On Twitter she said:
“I am a warrior, and I will never quit #ShitHappens haha be back soon.”
Felice Herrig did notice a funky smell during the fight, and prefers not too comment just to show respect to her fellow fighter.
This is not the first time an athlete, to be more specific a fighter made a dirty scene during a fight. Yoel Romero (13W-1L) also had a similar shitty moment.