Definition from Wiktionary, the free dictionary
Alternative forms 
- (idiomatic) A placeholder name for a person or thing, used when a name is not known; a generic name.
- She told me to ask so-and-so, but he didn't know, either.
- Some thing or things.
- He will tell you to do so-and-so, but read the instructions first, anyway.
- (euphemistic) Used for epithets such as SOB, bastard, etc..
- That miserable so-and-so messed up my work!
- See also Wikisaurus:whatsaname