Instructions are always interesting. I’ve both given and taken instructions in a relationship, I’ll be honest, mainly given. Lack of underwear was a regular one with one girlfriend, wearing an opaque enough top with a brightly coloured bra in a busy pub, which she was instructed to remove when she went to the toilet. No one could actually see anything apart from occasionally the shape of the nipples, but most of the blokes in the room spent the rest of the night trying to see. She did have somewhat of an exhibitionist streak though, not one to try if someone would be humiliated by the experience.
There may possibly be scope for setting each other challenges, but we would have to know a bit about the person we were setting challenges for.