look up any word, like hipster:
 
2.
'Gone south.' 'Lost it.' 'Non compos mentis.'

This term reflects the fact (for some) that
functioning (in whatever capacity) can be
severely limited on this day because of
its historic role as a down-easy day.

The term is not restricted to Sundays. It is
a cognate of the verb 'to sunday', meaning
'to underdo', 'to function at a low level'.
Man, did you catch DeeCee's slack getback.
He really sundayed it. Wait until tomorrow.

by Ward Smith March 01, 2009
 
1.
To get severely drunk, in a manner to which you have no recollection the next day.
Man up, lets get sundayed
by Sakky January 23, 2011