It's when you get into a physical altercation with someone for a wack, or stupid, reason.
Don't you DARE go spazzy wacky with me, boo! The shade I threw yo' way is REAL!
It is when one gets physical and wack, as in physically altercating.
Listen, boo! You can't go spazzy wacky on me just 'cuz I threw shade at you! React to my shades with better shades, not with your fists, unless you can't even afford a shade... Ahaha! Now can I get a Rayban? Oh, wait! I'm already wearin' one! No wonder this room looks so shady!