Spanish-English Slang originating in South Texas. Something that is so incredibly gacho or bad that it is hardcore. (short form of gacho = gach, joined with the word hardcore).
Wow that dude just totally called you out in front everyone at your birthday party, stole your girl, ran over your dog, and drew a mustache on your moms photo... that was way gach-core!
ayon kay Christy J. Quilantan ika-17 ng Nobyembre, 2007