To become highly intoxicated from alcoholic beverages, in such a state that the host can not stand nor speak. Derived/Inspired ny the character 'Stepehen James' who becomes 'Stiggied' at every available opurtunity.
The most common uses of these sentences happen (mostly to me) while laying in bed at night.
"Oh, that one boy, Shiggity Sean, what a dreamy man. I can't wait to stare at him later... Oh, Shiggity Sean!!!"- Mom walks into bedroom asking if you are okay, you say yes, she leaves, and you keep fantasizing about the almighty Shiggity Sean.