Do you need an alarm in your brain?

Many things we use every day have alarms that go off and warn you. For example a car has a warning chime or light to let you know your fuel is low. Car alarms sound off to warn a person that they are too close to your car. If you were able to have an alarm installed in your brain that went off automatically what would that alarm be for and when would it go off?

This is going to sound odd but I need an alarm which would go off every time I'm being too trusting and headed toward being taken advantage of. I tend to lunge head first into things while all the time I'm totally trusting either the person or the situation and I lose sight of my own best interest in the process. I can't tell you how many times I've gotten burnt, taken advantage of or got into a situation that was waaaaay over my head. I need a siren to go off with glaring flashing red neon lights spinning around the room in front of me.