Once when working in the marketing department of a UK company, we ordered 40,000 scratch cards which were for taking to Exhibitions and Trade Shows. The idea was that people would put their contact details on the back to claim the scratch card prize they had won. We could then market to these people as potential new customers.
The only problem was that even with all the checking and double checking that had been done at the 'proofing' stage of these cards, no one noticed that the contact details requested didn't ask for the phone number!
As the project was my responsibility, I ordered a custom made rubber stamp with a telephone symbol and a dotted line and hand stamped all 40,000 of them, adding the telephone contact details line in time for the first trade show! Now that really was tedious!