When your banging your partner and then soon you start shoving your penis into her anus, and you try to shove it until it touches her sphincter, and then after minutes of shoving, you cum a painful stream into her anus. Named after the aerial stunt from MLP: FiM.
Last night, dude, I started giving your mother the sonic rainboom and she was like, "OWWW!!! STOP IT!!!!".
by A Really Bucking Fastard January 17, 2013
Top Definition
1) When a pegasus pony breaks the sound barrier in flight, resulting in a rainbow and a sonic boom at the same time.

2) The most amazing fucking thing to ever happen on television.
When trying to catch her falling friend, Rainbow Dash unintentionally performed a sonic rainboom.
by AwesomeSauce42 October 24, 2011

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