Yoshimi Battles Beyonce
I think I've finally figured out why "Irreplaceable" isn't as irritating to me as Beyonce's other songs (at least in terms of the tune... the lyrics and rhyme-scheme are still bad): it's basically the same melody, albeit faster, as The Flaming Lips' "Yoshimi Battles the Pink Robots, Pt. 1." Seriously, the chord progressions are almost identical. Listen for yourselves:
Beyonce vs. Flaming Lips