Seriosky actully means: "Am lying", and you Know it"
This comes from all the politicians, crooks and others who have used the word "seriously" when they were actually lying, e.g: "Seriously, am Innocent-Robert Blake","Seriously, am innocent-Martha Stuart","seriously, am straight"-Ryan Seacrest

Someone who doesn't know how else to take things, and if they did, they'd be someone else would they not?

Seriously (used to add emphasis), or also to express cynicism or incredulity ('you cannot be serious').

Late 20th Century revival, predominantly in Munster (Ireland), of a term first believed to be in use during the inter-war period in Britain. Neither the origin nor the reason for the revival are clear, but it is thought that there are some examples in the literature of Wodehouse & Waugh.

A phrase used in south dublin whenever one needs to express shock , surprise , a dramatic expression , can also be said out of nowhere to surprise your friends

To be dead serious. To swear to God. A tense situation

A comeback that works on any insult.

A sarcastic whay to say, 'this is stupid'.