The phrase "when you walk by every night" is from the song "Fantasy" by Mariah Carey. In the song, the lyrics describe the singer's feelings when she sees someone she is attracted to passing by every night. The full lines go: "Oh, when you walk by every night
Talking sweet and looking fine
I get kinda hectic inside
Mmm, baby, I'm so into you." The lyrics express the singer's sweet fantasy and strong feelings of infatuation triggered by seeing this person regularly at night.