A pedant would have pointed out that the "No" should have been enclosed in quotation marks, as it's something you're asking them to say. Otherwise, the meaning is ambiguous - it could be 'Just say "no kids"', implying - incorrectly, so far as I am aware - that Calpol (day or night) is a viable form of contraception.
( Happy Phantom has been to Hastings, Brighton, and Eastbourne too, Sat 18 Sep 2010, 22:11, Reply)