Source: TMKOC
Dialogue: "Jethalal: Kuch samjhe? Friend: Nahi aap? Jethalal: Main toh bilkul hi nahi samjha. Friend: Toh main kya khaak samjunga!"
Jethalal is having a confusing conversation with his friend in his living room, where both of them admit that neither of them understands what is going on.
This is used in situations where a discussion is so confusing that both parties end up clueless, highlighting the irony or stupidity of a situation.