Indeed, this a criminally run brothel/arena, I don't really see jello wrestling as anything other then a side show for entertainment at a bar..... *light-bulb dings in head* ... how about you can schedule events for some buildings, either assign them set schedules for every week like you can schedule jobs for girls, , or have them as special actions you can take that cost a bit of cash.
for idea one, you could have the bar set to strip for day shift, and it draws in some brothel customers for that shift and gives dancers a bit of cash, and for night shift you can have like a private donkey show or other bar type entertainment, which earns thee girl and you more cash, but doesn't draw customers,/other misc. effects.
for idea two you could just have the donkey show/etc be a one off event that nets you like 2-4 k depending on the girls bestiality skill, with a downside of really tiring the girl out, or damaging her health/happiness and if shes a non-slave she demands her cut.