The phrase "Sittin' in a Tree" is a direct play on the classic, century-old American playground rhyme used to tease children about perceived romantic pairings:

[Name1] and [Name2] sittin’ in a tree K‑I‑S‑S‑I‑N‑G First comes love, then comes marriage Then comes a baby in a baby carriage

Without definitive proof, the beauty of “Nicole.and.Nita.Sittin.in.aTree” lies in its ambiguity. It functions as a mad lib for the digital age—anyone can plug in two names they care about.