My personal favorite, from a stall in the University of York in the UK (my alma mater):
There is nothing in life so overrated as a bad shag.
And nothing so underrated as a good shit.
Close runner-up was the handwritten addendum to a sign saying “Please do not throw cigarette butts in the urinals”:
… it makes them soggy and hard to light.
I haven’t seen this one posted yet: In the bathroom I once saw that someone had written notes under the instructions on the hand drier saying “press button … receive bacon.” Looks like it’s a real meme nowadays (see attached image), but I cracked up the first time I saw it.
A dozen more below:
Finally! A thread to which I can possibly add!
My favorite stall in college had two remarks that were stacked on top of one another. The stall scrawls were written in different handwriting:
There’s corn in the my poop
Better than the other way around
UCSB, circa 1975, inside a stall at the bottom of the door, about 8 inches from the floor: “Beware of limbo dancers.”
When I was a student, anti-nuclear demonstrations were big. Some sanctimonious person wrote in a stall, “You can’t hug your children with nuclear arms.” Someone thoughtfully replied, “No, but you can prevent them from wetting the bed.”
When I was an undergraduate at the University of Chicago, I saw in a bathroom stall in the Math Department’s Eckhart Library the following text written just above the toilet paper dispenser: “U of C diplomas. Take one.” I laughed then complied.
Above the urinal in a men’s restroom at a golf course outside a small ranch town: “This is the only place on this course where somebody won’t try to correct your stance or adjust your grip.”
Another sends a brilliant NSFW ad we posted several years ago when it first came out:
I saw this today, and I thought it fit well with the theme. Wait for it!
Spotted above a urinal in Michigan decades ago and never forgotten (probably because it’s all too true):
No matter how much you shake and dance
The last few drops go down your pants
I remember this graffiti from back home: “More than three shakes is masturbation.”
In the men’s room in the library of the University of Amsterdam: “Here I sit and contemplate, do I shit or masturbate?”
Not graffiti, but a note from the management posted behind the urinals in a restaurant men’s room in Cottage Grove, OR: “We aim to please. Will you aim too, please?”
I can’t believe I’m adding to this thread, since I’m a 66-year-old grandma now, but here it is: Many years ago I was at a little bar in the Des Moines suburb of Urbandale, and on the back of the door in the women’s restroom was a glorious big poster of a gorgeous man, bare to the waist, with Levis low on his hips that were unbuttoned down a couple of buttons (and this was in the late ‘60s when such eye candy was very unusual and very provocative). On the bottom of the poster was written in pencil, “What’s waiting out on the barstool for you?” I’m sure there were a lot of unhappy guys in that bar who couldn’t understand why they just couldn’t score there.
And last but not least:
This bathroom graffiti from a pizza joint in Tallahassee is wonderful:
“Anything will work as a dildo, if you’re brave enough.” – A. Lincoln