the expression used to be common among Anglo-Indians, e.g., "My new Arab is the real chīz"; "These cheroots are the real chīz"
*kʷo- became Latin quī "who", the dative plural of which is quibus. The OED says quibus occurred frequently in legal documents and so was associated with unnecessary complexity. It was borrowed into English as quib "An expression or point that serves to delay or obscure an argument; a quibble", and "A jibe, a taunt; a quip". It was later altered to quibble.