look up any word, like eiffel tower:
 
1.
When A Man Is Half-Erect.
Look At Tommy, He Is Half-Staff. Will It Do The Trick For His Girlfriend?
by Kevin January 26, 2004
 
2.
To have a half boner or chubby
When you think a hawt girl is looking at you u might be Half Staff
by J Stroke October 11, 2009
 
3.
A pejorative term for a bisexual
"Uh oh, Tony's acting the half-staff again. Crypto-dyke."
by Wangbacca February 05, 2009