Train yourself, no. Evolve it? Yes. But you'll need an awful lot of generations. Put a robot gun where everything has to come to drink--but it's an air rifle, calibrated to the point of maybe causing injury. Every year you raise the pressure by a tiny bit.

The reason you can't evolve bulletproofness is that it's an overwhelming force. You get evolution when you subject your target to something that only gives a partial kill.