Forgive me if this is a YART, but I'm new here. I really like tongue-twisters. What are your favorites? Hardest, silliest, rarest, strangest?

I like this one from Gilbert and Sullivan (actually a song, of course!):

To sit in solemn silence in a dull, dark dock,
In a pestilential prison with a life-long lock.
Awaiting the sensation of a short, sharp shock,
From a cheap and chippy chopper on a big, black block.

a bit difficult:

She makes a proper cup of coffee in a copper coffee pot.

I find this one quite difficult:

The sea ceaseth and sufficeth us.

(try to say it out loud a couple of times without looking)

and silly:

Odd birds always gobble green almonds in the autumn.