Top definition
When you are so tired that you unexpectedly fall asleep causing your head to whips downward then you often whip your head back up again. This usually happens in a seated or upright position.
Wow! Did you just see Seth sleepbang and then smoothly pass it off as listening to punk rock?!
by EssEeeTee April 16, 2018
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2
When you wake up and bang (coitus) and then go back to sleep.
"I was involved in the sleep bang last night! That is why I can't stay awake at work, boss!"
via giphy
by MCLovin2011 January 28, 2017
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