Interesting/strange things in your countries postal history

What are some interesting, or strange, things that happened in your countries postal history: i.e. the strangest thing ever mailed? Or, smallest post office, strange stamp issues, strange postal laws, etc.

I'll start with the United States Post Office mailing babies. When Parcel Post began on January 1, 1913, it was cheaper to mail babies, than to buy a train ticket. The First Assistant Postmaster General decreed an end to the practice on June 14, 1915.

from www.smithsonianmag.com/smart-news/brief-history-children-sent-through-mail-180959372/

Uniformed Letter Carrier with Child in Mailbag - Smithsonian Institution