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.
by Lonny the Big Dicked Bastard December 5, 2015
Get the hecksidy mug.