Tongue twisters!
Got a tongue twister in your language? Post it here! Here's a popular English one:
Peter Piper picked a peck of pickled peppers;
A peck of pickled peppers Peter Piper picked;
If Peter Piper picked a peck of pickled peppers,
Where's the peck of pickled peppers Peter Piper picked?

Question

Tongue twisters!
Got a tongue twister in your language? Post it here! Here's a popular English one:  
Peter Piper picked a peck of pickled peppers;
A peck of pickled peppers Peter Piper picked;
If Peter Piper picked a peck of pickled peppers,
Where's the peck of pickled peppers Peter Piper picked?

Answer

I have a similar one in Spanish, but it's very easy :p

Pepe Pecas pica papas con un pico;
Con un pico pica papas Pepe Pecas

and another easy one:

Tres tristes tigres tragaban trigo en un trigal;
Tragaban trigo en un trigal tres tristes tigres

Answer

I got some Swedish ones here:

Sju sjösjuka sjömän sköttes av sju undersköna sjuksköterskor på skeppet Shang Hai.

Knut satt vid en knut och knöt en knut. När Knut knutit knuten var knuten knuten.

Don't forget, you have to say them ten times in a row as fast as you can without a misstake. If you manage that, You're a Tonguetwister champion!