Early in my apprenticeship as a signpainter, around 1979, I was asked by another shop to come and cut out the masking for a huge electric sign face. This was obviously back when clear faces were painted from behind. It was a replacement for one side of a huge electric sign that was for a pharmacy. I used the pattern I was given. After I had cut the 4 foot high letters out of the word PHARMACY, I stood back and noticed the R was missing! Yep, it said PHAMACY. I pointed it out to the shop owner. He said "well, you're the first person to ever notice it and that sign has been up for years. I guess I don't need to tell you to keep your mouth shut about it". A few days later I drove my wife 20 miles to see the sign after the replacement face was up. When I asked her what the sign said she "pharmacy". I should add she graduated magna cum laude the next year from her university.