In terms is “surprise” I’d have to say it was my first CNC experience. This was in the context of a personal relationship. We’d negotiated limits and agreed to the idea but I didn’t know exactly when or if it would happen or what exactly would take place.

Turned out to involve strict bondage,being ordered not to cum and then having a Hitachi magic wand applied for as long as it takes. grin

I was shocked to discover that she was serious and that I was getting punished for disobedience ( capsaicin on cock and balls followed by caning on inner thighs) and was getting left in bondage until I was fully aroused and we could play again. Absolutely Hated the experience while it was happening but love the memory and 100% was willing to do it again shortly after.