What are the most common "killer phrases" that kills a persons creativity?

Look out for killer phrases that start with "That’s a good idea, but ..."

It’s against company policyIt’s not practicalIt’s not necessaryWe don’t have the resourcesIt will cost too muchWe’ve never done it that wayOur customers (or vendors) won’t like itIt needs more studyIt’s not part of your jobLet’s make a survey firstLet’s sit on it for a whileThat’s not our problemThe boss won’t go for itThe old timers won’t use itIt’s too hard to administerWhy hasn’t someone else suggested it before? Let’s form a committeeWe should wait until the economy improvesWho else has tried it? Is it best practice?