Posties, indulge me, what's the strangest thing you've found in a postbox or had to deliver?

Bear with me, I'm a touch bored, and reckoned breaking up the typical forecast of "Where is my parcel?" posts for my own amusement. I encountered this post online where a postie discovered a packet of sliced bacon had been posted. It got me wondering, what is the strangest thing you've found on your rounds?