What is the ruling on one who has anal intercourse with an unfamiliar woman or fondles her without intercourse? And what is the ruling on a person demanding to be called by a specific name if his companions call him by his grandfather's name, which he dislikes?

Penetrating a non-mahram woman in her anus is considered zina (fornication/adultery) because it is intercourse in the private part of a woman over whom one has no ownership or semblance of ownership. It is an abomination, as Allah Almighty says: "Do you commit indecency?" The perpetrator must offer sincere repentance, frequently seek forgiveness, and perform righteous deeds.

As for foreplay, please refer to Fatwa No. 42794.

Your colleagues should not call you by a name or nickname you dislike, based on the Almighty's saying: "nor defame one another by nicknames."