Cafe

I bought 10,000 shade balls and tried to swim in them. They appear to act like a non-Newtonian fluid: rigid under high shear stress, but they flow like a liquid under low shear.

You and your brother have discovered another realm and set off exploring the new wonderful world. Along the way, you see a troll catching creatures in an enormous net. The troll agrees to release the creatures if you can come up with a statement that is both truth and false. Can you come up with the correct sentence and force the troll to release them?