This is how it worked for me (true story):
My girlfriends sister (25yo) was in the shower when I turned up at their house and obvioulsy didnt hear me arrive. So she thought it was safe to do the 2 metre journey from bathroom to bedroom when she was done.....unfortunately (for her) that was the exact time I walked around the corner (on my way to the girlfriends room) and saw her fully naked. After a bit of screaming she ran back into the bathroom, not before I copped an eyeful though.
My girlfriend and their mum heard all of this so it was an awkward evening after that.
Mine wasn't premeditated and sinister like yours sounds though!
