One thing that annoys me about funny 404 pages is that they tend to assume that either a) the content referenced by the URL was deleted intentionally, or b) the user mistyped the URL. While in practise, the majority of the time I hit a 404 page, it is due to malpractise by the webmaster. A 404 page has to be very funny to offset the fact that it often is very unhelpful and blames the user for the webmaster's faults. (Fortunately, I found the FT Page submitted that funny, unlike many of the others in the comments.)

In that light, I find 404 pages like these refreshing for recognising the situation for what it is: https://two-wrongs.com/404