“Sweet fancy Moses!” is an exclamation that was used twice on the New York City-based television sitcom Seinfeld, on the episode “The Little Kicks” that was written by Andy Ackerman and that originally aired on October 10, 1996. Elaine (Julia Louis-Dreyfus) embarrasses herself dancing, and George (Jason Alexander) exclaims, “Sweet fancy Moses!” Jerry (Jerry Seinfeld) later sees the dance on videotape and also exclaims, “Sweet fancy Moses!”
 
“Sweet fancy Moses!” means the same thing as “Holy Moses!”
 
 
Wiktionary: holy Moses
Interjection
holy Moses
1. (mildly blasphemous) expression of surprise, outrage, disgust, etc.
       
Wikipedia: The Little Kicks
“The Little Kicks” is the 138th episode of the American television sitcom Seinfeld. This was the fourth episode for the eighth season. It was originally broadcast on the NBC network on October 10, 1996.
 
Plot
Elaine reluctantly allows George to attend a company party. George attempts to hit on Anna (Rebecca McFarland), one of Elaine’s employees, but she doesn’t seem interested. George is then horrified when he sees Elaine dancing at the party (to the song “Shining Star”), a dance which causes her staff to lose all respect for her.
     
Seinfeld Scripts
The Little Kicks
Episode 138
First aired: 10/10/96
Written by Spike Feresten
Directed by Andy Ackerman
Cast:
Jerry Seinfeld himself
George Costanza Jason Alexander
Elaine Benes Julia Louis-Dreyfus
Cosmo Kramer Michael Richards
(...)
Elaine: Oh sure. Hey guys, I wanna make a toast. Um… Here’s to us who wish us well, and those who don’t can go to hell… All right, who’s dancin’? C’mon, who’s dancin’? You want me to get it started? I’ll get it started. Whew! (She dances)
 
George: Sweet Fancy Moses!
(...)
Kramer: Well, I gotta give him something. Come on, where’s that tape I shot? 
 
Jerry: I think that’s it. (They play it and see Elaine dancing) Sweet fancy Moses!
 
Newspapers.com
16 October 1996, Detroit (MI) Free Press, “Television” by Mike Duffy, pg. 4F, col. 2:
Goofball line of the week: Uttered by Seinfeld nutty buddies George and Jerry. After watching Elaine’s mind-boggling display of bad dancing, they each proclaimed, “Sweet fancy Moses!” Indeed. Elaine was a true disco disaster.
   
Urban Dictionary
sweet fancy moses
Although it may have earlier origins, first heard by most of the world on the infamous episode of Seinfeld, when George witnesses Elaine’s atrocious dancing for the first time, and exclaimed, aghast, “Sweet fancy Moses!”
Interjection/exclamation: “Sweet fancy Moses!”
by ChickenGrrl December 03, 2004
 
YouTube
Sweet Fancy Moses
Sep 4, 2013
Keonekai160
Elaine’s dance
 
Twitter
NBC Entertainment
@nbc
Sweet, fancy Moses! #Seinfeld’s “The Little Kicks” premiered 20 years ago today.
4:52 PM · Oct 10, 2016·Twitter Web Client