There are many reasons to choose to live child-free. Some very valid reasons are overpopulation, living with a smaller footprint on the planet, and not wanting to raise fodder for the war machine. Choose from these t-shirts and get the word out.
A checklist of things to do lists fun stuff and "have children" crossed off the list. Great way to get the point across that you have to choose to give up your life for kids or give up kids so you can have a life.