Yea its is a fun dare. I've someone awhile back have me the same dare.

I've just done the dare that you gave me in person above do your fetish: Wear your tightest pair of underwear and fill them up with marshmallows and leave them in for 2 hours.
At start I was like "sure, no big deal, marshmallows are not messy" but now I have many little bit of marshmallows stuck on my skin