It is rude to interrupt someone's dinner.
Bob has a question to ask his friend, but he knows that they are sitting down to dinner at this time.
Bob wants to ask their friend the question.
Bob waits an hour then calls his friend and asks him a question.
Bob calls his friend and asks them the question he has even though he knows that they're probably eating dinner.
Bob's friend doesn't mind giving Bob an answer since they aren't doing anything else.
Bob's friend is annoyed to be called up and queried by Bob while they are eating dinner.