Assuming you're moving soon, of course.
Here's a solid, any-occasion choice:
Although it's especially effective when dropped off anonymously in the office break room.
For when the get-well and sympathy cards just seem too namby-pamby.
I'd tell you what Hipster Cake does, but it's a really obscure activity. You've probably never heard of it.
Thanks to Anony M., Kris K., Lauren M., Dawn M., Gal N., Amy D., & Melissa K., who might go back to cards after this.