Speaking from experience, the sensation a male gets after urinating. A combination of goosebumps and slight jitters/shivers/shakes.
Can also occur when something creepy happens.
Also known as the PW's for short.
Adam: Broseph, I got the piss willies this morning.
Leary: I did too. I'm sick.
Adam: Yo, did you see that pic of ____ on facebook?
Chin: Yeah... gave me the PW's.