Most of the time you're free to just wander into anyone's base or settlement, looting draws, cupboard and and everything in between for all they're worth, but occasionally you'll come across a place that's booby-trapped. If you enter a room and hear the clicking of a mine that's been triggered or a trip-wire you've just walked through, there's a few second delay before it wipes you out. In this delay, switch V.A.T.S on to slow down time considerably, and it can help you locate the device itself. From there, if you're quick enough to narrow down the source and act lightning-fast, you can disarm it and avoid a trip back to your last save. It definitely requires split-second timing, but can be done if you react fast.
