check twice, run once

a new catch phrase (assuming it actually 'catches').

check twice, run once

 pretty obviously a derivative of a woodworking adage "measure twice, cut once", and with the same underlying meaning - double check what you're doing before you do something you might regret.

in this new context, however, it applies to running programs (or generally just clicking on anything) and the idea is to promote the use of multiple layers of security checks to stop something from activating if it happens to be malware.

(and why "run once"? because, although there have been examples to the contrary, it is not unheard of for a malware sample to appear to do nothing when clicked, thus prompting the user to click several more times)