Ersatz erudition, or how to snow your neighbor with a few choice words, unknown facts, and phony savoir faire. With high glee and no little chutzpah, the authors offer this soi-disant survival manual for cocktail parties and country weekends. Specific instructions: use foreign words casually; throw in obscure facts or make up your own; quote remote sources; master three or four phrases, and use initials freely (B.S. seems the operative one here). Infra dig? Indubitably. Meretricious? You bet. Terra incognita? Not at all. You've heard these phrases before, probably use them yourself, and can think of folks already following the hokey rules. Taken seriously, it's the kind of speaking that torments Edwin Newman and sends the folks at Webster's into finer print. Taken lightly for what it is, it can help you past the local bore or through a smoke-filled evening. More appropriate for the time of winning friends and influencing people? Ah welt, plus ca change, plus c'est la meme chose.