It's always fun to make humorous 404 pages.
During the Federal election here in Canada the party web sites were pretty funny about it. The conservative ads always said that Justin Trudeau is "just not ready". That was their theme. So when you got a 404 page on their site it said "This page is is Just Not Ready, like Justin Trudeau". Don't recall what the others had, but they all poked fun at the other parties.
This one I made is OLD, I suppose I should change it:
http://www.iceteks.com/404I need to update that site one day actually. There's some weird encoding issue and lot of characters show up as diamonds, super annoying.