Bang goes something
Definition 1 of 1
Pro Tip 1/3Sudden Disappointment
Emphasizes an unexpected end to a plan or hope, often used with a tone of surprise or resignation. 
We were all set for the beach, but with this rain, bang goes our sunny day out.
Pro Tip 2/3Colloquial Use
Mostly used in casual conversation amongst friends or family, not in formal settings. 
He's lost the ticket? Well, bang goes the football match this Saturday.
Pro Tip 3/3No Change of Mind
Conveys a sense that the opportunity is entirely lost, not just postponed or altered. 
Bang goes my chance of seeing the concert, since it's sold out now.