It was Rex Barney who used to say that. Since he passed away, no one else has done it.
I believe the sign was “Hit Sign! Win Suit”. It was sponsored by Abe Stark, who owned a Brooklyn tailor shop and later went on to become the borough president.
You’re almost right. It’s in the Fireside Book of Baseball (the first one), and it says, “Hit this sign and Abe Feldman will give you a suit absolutely free”. He’s wearing a glove on both hands! It was printed originally in The New Yorker.
I’d’ve thought steroid-related shrinkage would’ve depreciated them a bit.
I wasn’t almost right. I was completely right. The sign was put up by Abe Stark.
http://www.baseball-statistics.com/Ballparks/LA/Ebbetts.htm
http://www.nycgovparks.org/sub_your_park/historical_signs/hs_historical_sign.php?id=8684
http://www.projectballpark.org/history/nl/ebbets.html
http://www.walteromalley.com/thisday_02_10.php
The last link is to a photo. The others are to text or a painting.
Well, that’s all fine, but that not the cartoon I was talking about.
OK, I see now. You were looking for the cartoon and I thought someone was asking about the real sign.
Never mind…
OK, now I understand too. We thought we were talking to each other but we weren’t…
Get a room! 
I heard a presentation from a woman who was an expert on advertising and the Brooklyn Dodgers and the Abe Stark sign was so famous that it inspired the New Yorker cartoon. I imagine that the name was changed in the cartoon because the magazine didn’t want to give Stark a free ad.
In case you two would like some period comment on the real sign and the cartoon, the manager of Abe Stark’s shop said that he thinks that Mel Ott was the first one to hit the sign. The sign, being at the bottom of the scoreboard, was not easily hitable. Most drives that low would be caught by the fielder.
He also said that Hack Wilson did it 2-3 times, and they had to make up a suit special, as Wilson was a very short guy with giant shoulders. Gil Hodges had to be specially fit also.
In the George Price cartoon, the businessman wore a catcher’s mitt on one hand, and a fielder’s glove on the other.
In the US, I wouldn’t be surprised the usher would try to get a signed liability release. 
I remember a case a fan sued. The court ruled for the stadium of the theory of assumption of risk. Balls do at times get hit toward fans.
Actually, once I got straightend out what was going on here, I do appreciate the history lessons from both of you. I never realized there was all that in back of the cartoon; I just like it. Knowing the story adds something to it. Thanks!
At all U.S. baseball games, fans are told that they need to watch out for flying balls and bats and that they are assuming the risk when they purchased their ticket.
At Japanese parks, the stands usually have high fences or nets along the foul lines so fans who would be in the most danger of getting hit by a sharply hit foul ball are safe. The ushers also blow whistles when foul balls come in to the stands. The stadium in Kobe has a few seats which are in front of a fence, but the seats come with individual face protection.
I found the George Price cartoon on line here .
That is just bizzare. Why not go all-out and surround the field with plexiglass like a hockey rink?
In baseball, the umpire often discards the ball just because it hit the dirt on the pitch.
This isn’t just being snippy. Jim Bouton in his famous tell-all book “Ball Four” relates how Whitey Ford in his later years relied on cunning, guile, and a sharpened wedding ring to cut the ball. With his experience the cut on the ball was a distinct advantage.
He was made to stop wearing the ring, whereupon his catcher sharpened his shin guard buckle and managed to often cut the ball for him with a swipe of the hand.
Gaylord Perry made a living for a long time with what was almost universally presumed to be a spit/Vaseline/mud/sweat/something ball. He even admitted it in a book, but said he’d already quit. Then he pitched the same way for years after.
And there’s nothing more amazing than watching someone drop a tray with $25 worth of food/beer to retrieve a $5 ball.