This isn't one of those fake Internet signs; this is a real sign that I saw while on a business trip in northern Minnesota a couple of months ago.
And it reminds me of a conversation I overheard in the cafeteria when I was in high school -- must have been 10th or 11th grade. Gabe and a couple of other guys at the next table over we're talking about what losers kids that still masturbated were. I don't remember the exact conversation, but to paraphrase, it went something like:
"When I was a kid, I masturbated like a kid; when I became a man, I put my penis away."
It's not that the guys thought masturbation was sinful; it's just that if you didn't have a girlfriend to handle your affairs, so to speak, then you were just a wanker.