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1.
An orgasm for your head delivered by a "Headgasm" scalp massager. Only the best feeling in the world. Comparable to the feeling of a cold shiver down your spine, but on the top of your head.
That thing is like an orgasm, for your head! Headgasm!
by joell86 September 01, 2010
 
2.
When your head gets all tingly, an orgasm of the head.
Dude I totaly just had a headgasm after that head massage my girlfriend gave me.
by Facehole19843422 May 04, 2009