The the mentally handicapped, and thus often euphoric or hysterical state of mind that follows a night of heavy drinking.
"Sally was definitely on half-speed this morning after Edward 40-hands last night. At Breakfast she almost peed herself laughing when someone pointed out that her shirt was buttoned up incorrectly".
by Jogana Jallenstrom October 29, 2009
1 more definition
Bu She is All Half Speed LaSt Night
by Chris martinez AkA CujO September 29, 2006