What is Sundayed?
1.
'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.
See