Sounds ridiculous but tell them to get a dog first.. Me and my boyfriend got a puppy 3 months ago and we never realized how much hard work it is, it's worse than having a child! We definitely will not be having kids anytime soon! Puppies need so much attention and cannot be left alone for long periods of time straight away, we didn't realize how much we'd have to plan ahead just to arrange for someone to watch him for a few hours while we do some shopping! We love Cody to bits and know he is our responsibility but some people just don't understand how much of a commitment these things are, and a baby is 1000 times harder than this. Just after we got our pup my friend told me how she and her boyfriend had spoke about having a baby, i told her to get a dog, she did and I saw her two weeks ago and she now says she never wants kids. Worked a treat!