For this dare you'll need the help of your FWB:
Together, go to a park/forest/public place you're comfortable being naked in (but where you run the risk of being seen, the place has to still be public).
Once there, strip completely naked and hand him your clothes, including underwear (or just don't wear any, your choice). He will blindfold you and insert a remote controlled vibrator (he'll have the control), then will hide your clothes.
On all fours, you will have to find them. He will use the vibrator to distract you (making sure that you only edge, without cumming). You will have 30 minutes to find them all without cumming. If you can't, come back to this thread for a punishment.
For him:
Spoiler:
Make sure to make at least one piece of clothing [B]very hard[/B] to find. Hide the others at your will.
--
As for the edge, do it right before you're blindfolded (before you have the vibrator in), in the public place where the dare will take place. As soon as you're on edge, he should blindfold you and insert the toy.
The training is for Posture. Try to keep the best posture possible during the whole dare and the rest of the week after it.