Taarak Mehta Ka Ooltah Chashmah S01 E2520 The Big Surprise

"Problems Toh Hain Sabke Saath, Bas Nazariye Ki Hain Baat!"

Guests arrive at Gokuldham society and meet the society members. The guests inform the society members that they have to assemble in the Club House at 8:30 as a big surprise is awaiting them. What is this surprise?