* A misspelling: It could be a misspelling of a real word or acronym. Could you double-check the spelling?
* A slang term: It might be a slang term used in a specific community or context. Do you remember where you encountered this word?
* A personal acronym: It might be a personal acronym created by someone for their own use.
Please provide more context or information so I can help you figure out what "yitbos" stands for!