The Romilda Incident.

Peter decides a love potion and a truth potion hidden in chocolates are the best way to get Derek and Stiles to admit how they feel about each other. It was the perfect plan. Except the chocolates got mixed up. And then eaten by Derek and Stiles all at once...
This in itself would not be the worst thing Peter has had to deal with.
But now Derek isn’t so much running his fingers down Stiles’ arm as he is counting the moles. Literally. For the third time in fifteen minutes, Derek dots each mole, follows it with an Eskimo kiss, and says “One sexy mole for Derek. Two sexy moles for Derek.” And so on.
You can see the problem.