"Woops boom" is a declaration of pity to be used after something, like a pen or a child, takes a large fall. Often employed by mothers and babysitters. It is similar to oopsie.
Max fell off the slide.

Mom: Woops boom! Come here Maxie, I will give you a popsicle to make it better.

Gabi: Ah! I dropped my calculator and the batteries fell out!
Megan: Woops boom!
by Lady Catherine de Berge January 28, 2011
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