it's just funny. It doesn't really mean anything. I mean it DOES mean something, right? It means, "smack my ass. call me judy." But it's just ... out of the mouth of Jon Lovitz. It's hysterical. I would say probably 95% of English speakers have never used the phrase in their life. It's hard to translate comedy.

It's a funny little phrase which basically means, "Well, I AM surprised!!" There are a few other phrases like that. Here's a link. Feel free to use whichever one amuses you most! http://www.slate.com/blogs/lexicon_valley/2015/03/11/slap_my_ass_and_call_me_sally_and_variants_southern_exclamations_of_surprise.html

I have never heard of that expression and I am not a big fan of Friends, but it is quite obvious as a native English speaker what it means. It means : Oh wow, am I surprized, shocked. Very along the same lines is ' Well, I'll be damned ', when you can't believe something.