Sometimes there are situations when you'd like to describe someone saying something, but what exactly he says is less important than the rest of sentence and it can be easily ignored. Or in case when someone is saying some long and tedious speech and in your sentence you're just using "bla-bla-bla" instead. What's the word Japanese would use in such cases?
Other situation is when part of sentence is missing. In most cases during lessons or exercises. (Or when you heard something all but one word missing and describing it to someone.) Teacher then uses some substitute word like "something-something" instead, just to keep the pace when reading. What's the word Japanese would use in such cases?