Forty-two or "For Tea Two." While one of the most important questions asked maybe "What is the meaning of life?" How often is it asked? It is not asked very often. However, "What time is it?" is asked a lot more but is not as important. If you follow the train of thought (The importance of a question is increased by the number of times it is asked.), and you love tea it is clear that the question "One lump or two?" is asked a lot and is very important! So the answer to the question "One lump or two?" is two or "For tea two." or expressed in as few characters as possible 42. It is also more specific than just 2 because "for coffee one" could be another answer.
It may also be assumed that tea is black tea with cream and sugar because that is what was drank in England for the most part at that time.
What does this have to do with loose leaf tea? Well, nothing but the next time you are reading or watching "The Hitchhiker’s Guide to the Galaxy" by Douglas Adams and offer someone tea keep it in mind.
On the other hand, Douglas Adams said "I sat at my desk, stared into the garden and thought '42 will do' I typed it out. " So he thought it didn't have a meaning but what does he know, he is only the author.