FGSFDS
Harald Schmidt demonstrating proper fgsfds technique You could either say "figgis-fiddis" or "F-G-S-F-D-S", but however you say it, it is the one word that makes no sense whatsoever at all. It started when an anonymous replied to a post on 4chan with "fgsfds". A namefag, Oryan, then shopped the phrase into a pic of German talk-show presenter Harald Schmidt.
When somebody confuses you by saying something that makes no sense, simply say "fgsfds".
fgsfds is commonly photoshopped onto pictures of anyone pointing their index finger in the air.
The term probably came from Something Awful, imported into 4chan during one of their mass migrations. It's original meaning was likely an acronym for "For God's Sake Fuck Dis Shit", though it was long forgotten by then.