> I am not sure where term "ping you" came from

I assume it's like using sports euphemisms in the office to convey a concept... this is likely a military euphemism (from radar/sonar). On one hand I don't mind it because it removes the specifics about how the person will contact you, it just simply states that they will contact you (and the method may vary depending on the time of day/week). Sure, there are other ways to say that, just as there are other ways to say something is "on deck" or you're "punting" a decision.