I've always liked the Germania series. I was unfortunately outbid on this postcard when I saw it on
ebay:

The Farewell Hour of the 5-Pfennig Postcard
When the price of all foodstuffs is rising,
The Postmaster General can no longer keep silent.
That won't distress the patriot,
And instead of five pfennigs he'll gladly pay seven.
But hold on! The numeral secretly causes me pain,
Because "seven" is an unlucky number.
So for the peace of our souls,
They added another whole half pfennig.
(I didn't try to replicate the rhyme or meter.)