Teacher vs Pappu dirty joke

Ye Tab Ki Baat Hai, Jab Pappu 5th Class Mein Thha.
Uski Class Ki Ek Teacher Pregnant Thhi, Usko Dekh Ke Ek Din Pappu Bola
Pappu: “Madam Aapko Beta Hone Wala Hai Ya Beti?”
Madam Bade Pyar Se Boli: “Ye Baat Mujhe Kaisi Pata Hogi?”
Pappu: “Madam Mujhe Pata Hai Aapko Kya Hone Wala Hai, Aapko Ladka Hone Wala Hai”
Teacher Hairani Se: “Arey, Tujhe Ye Baat Kaisi Pata?”
Pappu: “Mam Vo Jab Aap Chair Pe Pair Utha Ke Beth Ti Ho To Ander Se Uski Mooche Dikhti Hai“