Spissflabbad literally means pointy-mouthed (spiss comes from the Swedish word spetsig and flabb is a dialect word for mouth) and to be spissflabbad is to speak in an overly refined, posh and affected way.
Someone born and bred in the upmarket Stockholm district of Östermalm would certainly be spissflabbad, but so too would almost anyone from anywhere north of Helsingborg without a strong working-class accent.
Watch the video below to see the word pronounced by a true Skåning (who wished to remain anonymous).
As you can hear, the final 'd' is more or less mute (as would be the case in Danish), so the word is pronounced something like speyisflabba.
The term has its origins in the differences between how Scanians and most other Swedes speak.
If you've ever tried to get your mouth (or perhaps throat) around the Scanian 'r', you will know that it is voiced right at the back of the tongue, like in Danish or northern French dialects (it is either an 'uvular trill' or an 'uvular fricative').
Pulling off Scanian's sharp diphthongs also requires considerable movement from the speaker's mouth.
So to a Scanian, the central Swedish accent spoken in Stockholm, Uppsala, Eskilstuna and Västerås, sounds like it is spoken right on the tip of the tongue, with little discernible movement of the mouth and lips.
The term is also, indeed perhaps most often, used to refer to other Scanians who have somewhat softened their accent, either as a result of living elsewhere or gaining an education.
For example this tweet: “Things you get to hear if you go home to, for example, Kvidinge, and you have lost your dialect and started to talk posh. “Have you become 'pointy mouthed'?”
Those interested in the Scanian accent can watch this video on the dialect's dipthongized vowels: