[Slenderman - Doctor]

Find a relatively quiet spot outside. The best place for this dare would be somewhere like a field or near some woodland (by a footpath).

You'll need...

String
Clothes pegs
Two sturdy planks/sticks
Socks and undies

The idea is to go somewhere and set up your own mini washing line. Use the two sticks as posts and tie a few lengths of string around the top until it's steady and thick enough to hold up right.

Then, using the pegs, attach some socks and undies. If you're feeling daring, use the underwear you currently have on as you do the dare. Then, once your line is set up, sit back and watch from afar as people walk by. At regular times, maybe head over to the line, strip, and swap some underwear over.

Or, instead, put it up somewhere, go for a walk and come back later to collect your underwear... if it's still there xD

As usual, other alternatives and suggestions are welcome