It's hard to get more multilingual than this site!
2750 entries in 108 languages!
I have many favorites. This one for example is good fun:
I am a mother pheasant plucker,
I pluck mother pheasants.
I am the best mother pheasant plucker,
that ever plucked a mother pheasant!
Just don't say it in front of your mother...
And this one's not easy to say three time fast either:
Six thick thistle sticks.
But what's really great fun is to try some of the ones in a language you do not know!
I was fascinated by the Chinese ones. I'll have to print them out and bring my tape recorder with me the next time I eat in a Chinese restaurant!
Click this link http://www.mamalisa.com/mp3/chinois.mp3to find out what it sounds like!
And there's something really special about this Danish one:
A æ o æ ø i æ å, æ a!
You'll have to click here for the translation...
By the way the tongue twister on the T-shirt is a famous Czech one with no vowels that translates roughly as "Stick your finger down your throat".