A postcard from the castle's 1987 renaissance...

...and a few variations of the rhyme behind the postcard. According to wikipedia, there are a few variations of the popular nursery song.  Among them:

Rub-a-dub-dub,

Three men in a tub,

And how do you think they got there?
The butcher, the baker,
The candlestick-maker,
They all jumped out of a rotten potato,
'Twas enough to make a man stare.

 I must admit, I have never heard this rendition before, but I like it!  Here's another:

Hey! rub-a-dub, ho! rub-a-dub, three maids in a tub,

And who do you think were there?
The butcher, the baker, the candlestick-maker,
And all of them gone to the fair.

Again, it's new to me, but fun. And it's bawdy: three respectable townsfolk "watching a dubious sideshow at a local fair." It's a ryhme about an early burlesque show, as it were. 

Lastly, the version I grew up with:

Rub a dub dub,

Three men in a tub,
And who do you think they be?
The butcher, the baker,
The candlestick maker.
Turn them out, knaves all three.

And, as promised, the postcard:

 Happy Monday!