You might say "blah blah blah" when you're not interested in what'd be said.
I sometimes say "whatever" to convey the same idea, which does not share the nice rhythm effect of "blah blah blah". As a non-native speaker of English, I often pronounce "blah blah blah" in a very awkward way when speaking out very quick.
Any alternatives for "blah blah blah"?