Have you heard the complaints by the younger Marines about being called Devil Dog? I guess the situation is usually that: Marine (A) has done something wrong, Marine (B) witnesses that error. Marine (B), in an effort to address Marine (A) and correct the problem will say, "Hey, Devil Dog!" ; then, of course, address whatever the error is. So, because Marine (A) doesn't like being corrected or maybe just doesn't like being caught, they have an attitude about being called "Devil Dog". Marines, just remember you are a Marine and act like a Marine. Then when you are called Devil Dog, there cannot be a negative connotation associated with it.