
As dull as dishwater
As dull as ditchwater / As dumb as ditchwater / What a bore! / Bore to death

Non sapere di niente 
Non sapere né di me né di te / Non sapere né di pepe né di sale / Non sapere neanche di acqua calda / Non sapere neanche di acqua bollita / Essere stupidi come l'acqua calda
As dull as ditchwater / As dumb as ditchwater / What a bore! / Bore to death

Non sapere di niente 
Non sapere né di me né di te / Non sapere né di pepe né di sale / Non sapere neanche di acqua calda / Non sapere neanche di acqua bollita / Essere stupidi come l'acqua calda
Meanings
Fig.: said of someone or something showing nothing interesting. To be extremely dull and tedious
Examples




Origin
It seems that the dishwater of this expression, alluding to the grayish water in which soiled dishes are soaked, came to be in the first half of the 20th century as a mispronunciation of the original phrase As dull as ditchwater, which referred to the muddy water of roadside ditches