Boxers Or Briefs

One day some guys were doing a survey between "boxers" or "briefs".

They went to a 25 year old man and said:

- boxers or briefs? - He said briefs.

They went to a 40 year old man and said:

- boxers or briefs? - He said boxers.

Then they went up to a 80 year old man and said:

- boxers or briefs?

And the old man replied:

- depends?