This is an update of the awesome script created by Rhomboid, and is shared here with his permission. Rhomboid's greasemonkey script replaces the default comment form buttons (Post, Preview) on MeFi, AskMe, MeTa and other subsites with a unicorn and narwhal. It should also show a laser kitty for the comment form on deleted posts (the laser kitty works at least on MetaTalk with the Modern theme, so hopefully it works elsewhere, too).
See Rhomboid's original script description and credits (with laser kitty screenshot) at the userscripts.org mirror.
Version 3.1: 2016-08-21 - Added "Modern" to @name to distinguish it from Rhomboid's script name. Removed extra ";" in "box-shadow" line and some extra spaces. (Minor syntax cleanup...version 3.0 still works for me.)
Version 3.0: 2014-12-31 - Updated version 2.0 of Rhomboid's script to add compatibility for Modern theme (got narwhal showing again for Preview button, added text wrap within Post button, stopped background image from changing position on hover); general style enhancements for buttons (added glow effect for better text legibility, highlighted border on hover). Should also still work with the Classic and Plain themes. Note: Laser kitty untested. Update: I've seen the laser kitty show up on a deleted thread on MetaTalk using the Modern theme, Dark Mode.
Version 2.0 - This is the (mostly) unchanged version of Rhomboid's script version 2.0, as it was last available on userscripts.org (see mirror). The actual code is identical -- the only change is that I had to add a @namespace meta line to be able to post it to greasyfork.org. (Uploaded here so you can run diffs to see what exactly changed from Rhomboid's code.)
Modern Theme, with default comment form buttons on MeFi:
Modern Theme, with this script enabled: behold the unicorn "post" button and narwhal "preview" button!
Modern Theme - Dark Mode, with default comment form buttons:
Modern Theme - Dark Mode, with this script enabled: