On the prank front
Didn't pull either at the office this year but was an instigator at someone else's by giving them ideas.

Just load it as a screensaver image - best effect is on laptops

A classic - tape also works but don't use scotch since some types are a pain to remove cleanly and you will have to deal with the grumpy IT Bugbear
With respect to librarian positions
Commercial publishers also have libraries of still photos, filler stories, artwork, ad copy, various media.
Same goes for companies that work in media or marketing.
These days there are also just raw files on desktops or servers, placed in various user folders as well as the general directory where you are no supposed to save anything, that need to be moved, renamed, indexed and archived.
Tangent
My baby sis, graphic artist [yeah-not exactly what most would call IT savvy], ended up doing this for the publisher she worked for because she was the most technically literate on staff.
She "discovered" an astounding amount of materials squirrelled away in file file folders, loose hard drives behind stacks of older magazines, shoe boxes full of negatives and more strange storage habits and media, that added up to an ungodly sum in value.
Place imploded when she left despite her having implemented a simple to use and maintain tracking database from yours truly. [freeware and I did it as a learning exercise]
I was surprised things lasted as long as they did having met the owners and a majority of the permanent staff.
On the sensible lunch option
I can never understand these diet fads and their twisting of language by marketing types
Light protein - what does that even mean?
Clean option - does that imply that contaminated lunches are standard and clean is an option?
I tried a quick lookup on healthy exam foods but the first few pages were all blogs and commercial diet sites and I don't have the energy to dig deep enough to find actual nutritional information not contaminated by pseudoscience or marketing or both.