Well I agree with several of the above (breast pump, breasts, muslins and morrck hoodie.
But for me I would say the Natural Womb sounds track downloaded from iTunes for 99p which is the only thing that stops N in his tracks when he starts screaming. It stops him every time without fail within a couple of minutes, but usually instantly and allows him to calm down and relax a bit so he doesn't start up again when the 'music' stops.
It is one of the most intensely annoying noises to me now, but it has actual magical powers and I wouldn't be without it under any circumstances!