Ok this is what I sent the guest (this one from booking.com)
I have another guest checking in this afternoon and while changing the studio I noticed that you left a expensive electric toothbrush, a fancy glide razor and some really nice metal handcuffs on my bed railing. I will keep these items on my side of the house if you want to pick them up since I know you live close by. Unfortunately the handcuffs that are hanging from my bed rail was left without a key and I will have to call a locksmith to open them for me and the cost will be deducted from your security deposit.
Please call me as soon as possible, perhaps you have the keys to the handcuffs and we can avoid the cost of a locksmith.
I laughed at first sight of the cuffs until I realized I could open them.