This is a cool thread. Maybe about 25 years ago, in South San Francisco off of the 101 freeway, there was this giant billboard. There no more, and one of my favorites, it was a simple design. Against an all-white background were black letters saying:
KEY PURE ICE UNDER ODE
(Ya gotta say it fast and tie all the words together)
Saw this sign while driving through the Appalachian Mountains:
Adventure Park
Unguided Horse Rides
Zip Line
That’s one helluva talented horse! 
One of my favorite signs is just west of Tuba City AZ. I get a kick out of it, but I think that not many people find it interesting. Nevertheless, I’ll share it here.
This sign is just west of Tuba City AZ. I was on a motorcycle ride from San Francisco to Phoenix.
If you turn left, it’s 70 miles to the South Rim.
If you turn right, it’s 150 miles to the North Rim.
This sign can make one think that the north and south rims are near each other. While as the crow flies they’re only about 10 miles apart, to drive it you’d have to drive 225 miles.
Not amused? Don’t say I didn’t warn you. 
In Munich back in the early-'80s I saw these three stores:
Wormland
Peter Palmer
Christ Schmuck
I like that one.
I found a Google Maps Streetview pic that is surprisingly bad.
And a different instance in the lower-left.
Christ Schmuck is a big German jewelry chain, you’ll see one of their stores in every bigger inner city. “Schmuck” just means “jewelry” in German, and Christ is a common German family name.
You put some effort into that. Thanks.
Yeah, my horse would definitely need a guide for that.
I knew that. It just looked funny in English.
For those who (like me) were wondering about the Yiddish word schmuck:
Schmuck, or shmuck, is a pejorative term meaning one who is stupid or foolish, or an obnoxious, contemptible or detestable person. The word came into the English language from Yiddish (Yiddish: שמאָק, shmok), where it has similar pejorative meanings, but where its literal meaning is a vulgar term for a penis.
The Yiddish word shmok derives from Old Polish smok “grass snake, dragon”.[2][3][4]
…
In the German language, the word Schmuck means “jewelry, adornment”.[5] It is a nominalization of the German verb schmücken “to decorate” and is unrelated to the word discussed in this article.[2]
I guess in some roundabout, linguistic twist, “penis” might be related to “family jewels.” 
Carry on.
Found in a police station bathroom:
I swear I saw one of a hot air blowing hand dryer that said press here for a speech by Trump.
Or receive bacon.
30+ years ago (so pre-internet) at one of the lavs backstage where only the union workers had access there was the same sort of dryer. With graffiti reading
Push button for latest Union 800 hotline recording.
So the idea isn’t fresh. I’m pretty sure there are plenty of trump-dryers across the land these days.
There’s a local place in Raleigh called Snoopy’s Hot Dogs. It was converted from an old service station and had a sign out front advertising specials, usually accompanied by a one-liner quip.
Sure enough, that got under the ass of some do-gooders who thought it was in violation of city code, so there ensued a hearing, which drew a lot of local support in favor of leaving Snoopy’s alone.
After the hearing ended, Snoopy’s new sign read something like “Snoopy’s wins lawsuit. Sentences City of Raleigh to reading the First Amendment.”
This might not be quite the sort of “sign” the OP meant but … I’ve talked about this previously …
There’s a beachfront tourist schlock shop near me. Which sells lots of “humorous” signs with cute sayings on them.
Several hits:
In dog beers I’ve only had 1.
I like going to the shore. The ocean make my butt look smaller
Came across this toy store in Naples, Italy:
Was initially confused, as back in Hawaii “pakalolo” means something else entirely. Here’s a hint:
Personally, I’m more amused by Arizona having a “Tuba City”.