The Y2K Bug Simulator adds filters to most core WordPress functions that report back a date, rendering 19xx in place of 20xx.
Screenshots

Screenshot demonstrating the effects of the plugin when activated. Note the changes to the page title, the post date, and the dates listed under "Recent Posts."
FAQ
Installation Instructions
- Upload
jbl-y2k.php to the /wp-content/plugins/ directory
- Activate the plugin through the ‘Plugins’ menu in WordPress
Why would I ever use this?
Well, it may be that I am too easily amused, but I find it mildly entertaining to see a site’s content labeled as pre-dating the internet. It is also amusing to turn the plugin on just as a significant date/time passes (such as a change in DST), and leverage the general uncertainty most people have about computers, dates, and time.
Also, nostalgia for the y2k end-of-the-world scare.
Will it work with insert_theme_name_here?
As noted above, the plugin will operate on almost all requests for date-related data that utilize core WordPress functions to do so. If you have code that utilizes dates that do not pass through core WordPress date display functions, you will not see changes in the output of that code.
Will it work with insert_plugin_name_here?
See above re: themes.
ChangeLog
1.3
1.2
- Tested up to WP 4.1.
- Added plugin settings page.
- Added option to limit visibility of Y2K effect to admin users (default).
- Fixed archive/calendar links for permalink formats other than ‘default’.
1.1
- Tested up to WP 4.0. Added icon.
1.0