Yiddish is the caring, authoritative inscrutability of your elders. It has rules, but they're mainly inherited from the tributary languages. It's inconsistent in a way that shows it doesn't matter. It sounds like a beautiful mess (which, considering its mainly Germanic origins, is quite an achievement). Well, it sounds beautiful to me, anyway. Others think it's just a mess - there's a famous National Lampoon "Teach Yourself Yiddish" piece that recommends you make up vaguely German/Russian-sounding words that start with "sch" and just string them together.