Wiktionary
whistle past the graveyard
vb. 1 (context idiomatic US English) To attempt to stay cheerful in a dire situation; to proceed with a task, ignore an upcoming hazard, hoping for a good outcome. 2 (context idiomatic US English) To enter a situation with little or no understanding of the possible consequences.
Usage examples of "whistle past the graveyard".
A brownie youth gang, chukos, way off their turf, played whistle past the graveyard, probably pray.
A brownie youth gang, chukos, way off their turf, played whistle past the graveyard, probably praying the local Travelers would not come out.
But of course, any fool who can pucker is apt to whistle past the graveyard.