look up any word, like ratchet:
 
1.
This is the reflex that naturally occurs in your sphincter muscle when you get unwillingly poked or proded in that area, the more surprised you are the stronger contraction.
When you joking poked me in the ass with that stick it made me have a sphighten.
by J Double Dubs November 06, 2007

Words related to sphighten

anal anus ass involuntary reflex sphincter