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When a lack of sleep/ energy causes a fully functional adult to 'zone-out', become forgetful or impatient, and possibly run in to furniture/ walls.
EXAMPLE:

'Why are you staring at the oven? You've been there for 5 minutes and haven't moved...'
'Sorry, I'm running on retard. Kitty kept me up with her fussiness last night... Didn't sleep a wink.'
EXAMPLE:
Walking out the front door and realizing you forgot your keys, then walking back inside only to forget what you went inside for until you try to lock the front door... AGAIN.
by TaTa Bondage January 16, 2011
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