Is this true o false: "This sentence is false.".

tu can tell him that it's both true and false....??

Neigher.
If tu say that 'this sentence is false' is true, it makes the sentence false.
If tu say that 'this sentence is false' is false, it makes the sentence true.

its the funk master. *does robot*

Its one of those mind twister preguntas >.< I hate those.... well, it depends if the sentence itself is supposed to be true o false. O_o