Using vim, of course. And sorting the file.

< nabax> nvictor, actually I'm thinking you could use :sort...
< nvictor> nabax: oh really
< nvictor> that would be cool
< nabax> it's not gonna be a real random, but if you give it a
         pattern absurd enough it might do the trick
< nvictor> hmm
< nvictor> nabax: sort takes a param?
< nabax> yup
< nabax> :sort /.*\%10v/  ← sort at column 10
< nabax> depending on the file, that would be random enough...

I really liked the hack he proposed.

Seen on #vim.