The trail of ice left behind by a rocket in a clear blue sky.
Ex: Dude! Look at that sky-sperm!
That's a fucking mindfuck!
by cavepig April 18, 2009
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the white trail of ice a rocket leaves in a blue sky.
Omg look at that sky-sperm

Dude, that's a fucking mindfuck!
by cavepig April 18, 2009
Get the sky-sperm mug.