Shacks definition.. hmm.. I guess shack could possibly mean, thinking of the most retarded thing you could say.. then saying it wrong. Definitely sounds like "Shack".. Getting jacked and doing nothing about it because your a bitch also sounds like "Shack" shifty and stupid just about sums it up.
! you almost pulled a shack there"
"Yo, I could never be as stupid as that kid"