Trousers and steeds
Who versus whom. I always think of whom as a recipient of an action or object. Who spanked whom? To whom did you give the merkin? But rest assured that nobody but a twat would correct you if you were to ask in conversation ‘who did you give the merkin to?’ So why do we worry about using whom at all? You’ll find the best explanation here (and it’s all about trousers and steeds).