When I have to provide technical support to a true dunce:

“The answer to that question can be found in a cursory examination of the documentation.”

When I’m chairing a meeting and one guy just won’t shut up:

“Thank you very much for that valuable contribution to the discussion, we will certainly take it under advisement. Now moving on to the next topic.”

And here’s one that I use when I need to tell a SO/GO/FO:

“Sir, that COA is beyond the scope of implementation for the currently available resources.”