Used to describe tobacco, most commonly used when describing tobacco in a joint. Also used by stoners making fun of cig smokers.
“Ayo Bobby, slide me some of that whacky tobaccy, I wanna roll a spliff.”
An alternative of whacky 'baccy embracing the name of a once-popular brand of English cigarettes (and which so much better than yanky-wanky ones)
TEACHER: Which one of you little sods has been smoking whacky Woodbines? Giv's one, you little bastard.
Testicles. See also tallywacker, whack off.
His whacky sack looks a little swollen!