I love forced choices and "This or That" type of predicament play. I've played where I was given a special safe word to end a predicament. The catch was it was also code for "Please give me XX strokes with the cane"

One of the best examples of this that i have ever experienced was about 20 years ago (i was much younger and far more flexible )

I was standing gagged(well crouching would be more accurate ) wearing a humbler and ankle spreader bar with my wrist cuffs clipped together behind back. My wrists with attached to an overhead pulley and I was put into the beginnings of a strappedo position. Trying maintain the crouch increased the Strappedo while trying to straighten up and ease my shoulders increased to pull from the humble.

The genius was she told me I was going to be kept in position for 60 minutes but if I wanted out early all I had to do was grunt loudly three times. The catch was one stroke with the cane for every minute I failed to complete.