In a general sense, to tell someone that they are boresighting means that they are too focused on something and need to look around and see what is going on.
P2: Dont Boresight theres a bogey at 6
P1: Oooh craaaaaaaap
or in a civilian environment
PI: lemme get this one done... im nearly there
P2: Dont boresight you have 34 more to finish