A sound effect used for the purpose of saying outloud when performing an action such as punching, kicking, throwing something, etc...
*Be sure to put a long emphasis on the long "oo" sound. Such as, "Blo0o0o0o0o0m!"
Gary is driving late at night back home when he decides to throw some trash out his car window. After he rolls it down, he shouts "Bloom!!!" as he chucks it out.
Thus, the sound effect adds to the boring-ness of just throwing it out without one.