What do you do when the sink is full of water? Pull the plug. What if it is filled up with creative ideas? You pull the plug. Why? Because it allows you to "think sink" -change your thinking in order to think about newer ideas than the last, to think sink away from them again, to allow, new creative ideas to emerge. Edward De Bono rerfers to "water logic" that is like a state of change of thinking, rather than rock logic which is static. The ideas from the think sink can be used but it is the thinking that developed those ideas initially that can turn stale not the ideas, so at this piont the tap needs to be turned on again.