Theory:

(Scene 11: Inside the palace)
Narrator: Gopal was brought before the king.

Courtier 2: It's Gopal!

Courtier 3: The man has lost his mind!
Courtier 4: I think it's one of his crazy jokes.

King: All right, Gopal. Out with it! Why are you dressed up in this ridiculous fashion?
Gopal: Your Majesty, You seem to have forgotten something!

King: Forgotten something?

Gopal: Strangely enough no one seems to be interested in Hilsa-fish today! From the market to the palace and the court, not a soul has spoken a word about Hilsa-fish!


(Scene 12)
Narrator: Only then did the king remember the challenge he had thrown to Gopal.
 
King: Ha! ha! well Gopal, congratulations! You have achieved the impossible once again!
Explanation:
 
Finally, the guard took Gopal in front of the king. On seeing the man in disguise, one of the courtiers understood it was none other than Gopal. The courtier exclaimed, "It's Gopal!"
 
Later on, the courtiers were talking about his appearance. One of the courtiers said Gopal had lost his sense and behaved like a mad person. At that time, the next one said he probably think it was one of Gopal's crazy jokes. From the second comment, it is clear that Gopal is a friendly person who enjoys entertaining others with his amusing jokes.

While the courtiers were reviewing Gopal's funny look, the king came out with a doubt. He questioned Gopal why he had dressed up in such a strange manner? At that point, Gopal began to remind the king of the mission he had been given. Gopal informed him that no one had questioned him about Hilsa until he arrived at the court. Instead, people were really curious to know who was that insane man. In this way, Gopal had succeeded in his task and reached the palace.

After hearing about Gopal's point, the king recalled the task assigned to him. Finally, the king congratulated Gopal on completing his goal, saying, "Ha! Ha! well, Gopal, congratulations! You have achieved the impossible once again!"
 
Meaning of the difficult words:
 
S.No
Words
Meanings
1
Lost his mindTo become insane or mentally unsound; to become extremely foolish
2
Ridiculous fashionSometimes intentionally dressing up to make people laugh or get their attention
3
Curious Eager to know or learn something
4
SucceededAchieve the desired aim or result
Reference:
National Council of Educational Research and Training (2007). Honeycomb. Gopal and the Hilsa-fish(pp. 36-47). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.