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After you wake up from sleeping and you lay in bed with complete silence relaxing. The only activity that can be done between is a morning pee. you must return to your bed and lay down for it to be fat sleep.
Joe woke up and layed in his bed fat sleeping for two hours, adding to his sloth like ways.

Joe: I fat slept for like 3 hours
Mike: You're a real slothman and a FOF to boot.
by Ih8umikelee May 12, 2008