70's Spot -- Coke Commercial or PSA: I Can't Remember?

Does anyone remember either a Coke commercial or a PSA from the 70’s with a teenage couple, boy and girl, and she says, “How come you never call me?” and he says, “How come you never gave me your number?” I remember a very close shot on them with their heads together, and I remember that the ad/spot itself was very short, and grainy—very gritty 70’s style, very urban, at least in my memory.