Anticlimax:

A sudden drop from the dignified or important in thought or expression to the commonplace or trivial, often for humorous effect.



Example:

"Nothing makes me want to disappear 

As when someone opens their mouth

 It's just my luck 

I get hit by a car 

While carrying a cake 

 Dripping cherries 

Onto pavement 

Bride and groom on my face 

 I'm not there like a ghost ship in a storm 

 It only figures 

That I'd ride my bike 

And as I'm sinkin' 

The last thing that I think
Is, did I pay my rent?"
-Jim O'Rourke, Ghost Ship in a Storm


Explanation:
O'Rourke uses an anticlimax at the end of his song. The purpose of this is to add a humorous tone, it also helps characterize the narrator of the song as one that has given up hope. Before the anticlimax the lyrics build up adding suspense, when the anticlimax comes it creates a funny ending, to show that this is not very serious. The purpose of an anticlimax is to add a lighthearted and upbeat spin on the climax, and that is exactly what O'Rourke did.