Spoiler:
Dhbgvat fcbvyref fubhyqa'g or oebxra nsgre guvf. Gur byq barf jvyy erznva hadhbgnoyr, ohg arj barf fubhyq or

As far as the PRE tag, it causes more problems then it solves, as a long spoiler won't be word wrapped properly, and manually word wrapping caused even weirder issues. For now, just hover over the beginning of a spoiler.