A known line in the Love Live fandom from the song¨ Kimi no Kokoro wa Kagayaiteru Kai?¨ from Love Live! Sunshine. The combination of these words doesn't mean anything (doki doki portrays the sound of a beating heart).
Person A: What's that one line from Kimi no Kokoro wa Kagayaiteru Kai again?
Person B: It's obviously Oh yes! Doki Doki Sunshine!