"Holy Machinaw!", is a familiar phrase/expression by Joe Bowen, during Leaf games; It is what he saids, to explain an act of greatness; But, what is a 'Holy Machinaw'? I believe, it is comes from the word 'machination'.
Webster defines it as:
1 [Rare] the act of machinating
2 an artful or secret plot or scheme, esp. one with evil intent: usually used in pl.
What was your greatest, Holy Machinaw! moment?
What is your greatest, Holy Machinaw! fantasy?
It would be an epic Holy Machinaw if the Leafs were to make the playoffs this year  or win a Stanley Cup.