(as) dull as dishwater

US /əz dʌl əz ˈdɪʃˌwɔtər/
UK /əz dʌl əz ˈdɪʃˌwɔtər/
"(as) dull as dishwater" picture
1.

very boring or uninteresting

:
•
The movie was as dull as dishwater, I almost fell asleep.
•
His presentation was as dull as dishwater, full of facts but no passion.
:
dull