If something has no intelligent meaning, you can describe it as nonsensical. When you're really angry, you might hear yourself sputtering nonsensical sounds and have to stop, take a breath, and start again.
Lewis Carroll's poem "Jabberwocky" is full of great examples of nonsensical words, like "mimsy," "frumious," and "slithy," which manage to be both descriptive and completely nonsensical. Something that is utterly ridiculous or absurd can also be described as nonsensical. You might tell your best friend, "I know you like crazy hats, but that thing on your head is completely nonsensical."