Ruling on asking passers-by about songs they know, then asking them about religion and the Qur’an to highlight their ignorance, and publishing that

Firstly:

It is haraam to harm believers, expose secrets and find out their faults.

Allah, may He be exalted, says (interpretation of the meaning):

“And those who harm believing men and believing women for [something] other than what they have earned have certainly born upon themselves a slander and manifest sin”

[al-Ahzaab 33:58].

One kind of annoying people and exposing their secrets is what you have mentioned, which combines two haraam things:

1. Making a person speak openly about his sin, by mentioning what he knows and listens to of songs and the like.
2. Exposing his ignorance of religion, or his inability to recite Qur’an, or his lack of knowledge of the Sunnah. This is harming him, his family and his relatives and exposing him to mockery, and encouraging viewers to  mock him too.

Secondly:

No one has the right to ask anyone else a question that will lead to him speaking openly of his sin, because the Prophet (blessings and peace of Allah be upon him) said: “All of my ummah will be fine except those who commit sin openly, and it is part of committing sin openly for a man to do something at night, then in the morning when his Lord has concealed him he says: ‘O So and so, I did such and such last night,’ when his Lord had concealed him all night, but in the morning he discloses that which Allah had concealed for him.”

Narrated by al-Bukhaari (6069) and Muslim (2990).

And he said: “Whoever conceals (the fault of) a Muslim in this world, Allah will conceal him (his faults) in this world and in the Hereafter.” Narrated by al-Bukhaari (2699).

All of this applies if recording and publishing of that is done with the knowledge of the person being asked.

However, if that is done without the knowledge or permission of the one who is asked the question, with regard to the recording first of all, then with regard to publishing it, as happens in some foolish and immoral shows, then undoubtedly that is a great evil and transgression, and is violating people’s dignity and privacy.

Conclusion:

This action leads to something that is haraam both for the one who is asked and the one who watches it. So what should be done is to turn away from such things in all circumstances.

And Allah knows best.