What is a type of word that can mean anything?
For example, there's a cartoon where the characters would say "Smurf" to refer to anything. It seemed to be used as a noun or verb.
There was another cartoon where the characters in the society would use the world "Og" to mean anything. It could be used in place of any word. Somehow, oddly enough, it is sometimes surprisingly easy to infer the meaning.
Bonus example, there have been movies where one guy talks to his friend and exclusively uses the word "dude" in a brief conversation. Somehow, oddly enough, it's also sometimes surprisingly easy to infer the meaning. :P
Is there a word that describes the type of word that is any word or almost any word? Wildcard word? Super word?
Can we invent the word if it doesn't exist? Why not?