Some examples:
Quanto fanno due piu' due?
Boh!
How much is two plus two?
Dunno.
Qual e' il significato della vita?
Boh!
What is the meaning of life?
Beats me.
Perche' la gallina ha attraversato la strada?
Boh!
Why did the chicken cross the road?
Search me.
Toc toc.
Chi c'e'?
Boh!
Knock knock.
Who's there?
Have no idea.
Essere o non essere?
Boh!
To be or not to be?
Hell if I know.