Meaning many or very. An ambiguation of "hecka" synonymous with "hella". Mainly used by children in Nor Cal especially in the Bay Area to emphasize "hecka" and denote even more than hecka.
That girl is hecksidy fine.
I got hecksidy candy for Halloween.
A scrub, dipshit or otherwise useless and moronic idiot, potentially worthy of getting their ass beat.
If that zark keeps talk shit heâs going to get laid out.