This is a complete shot in the dark, but I'm going to say "The Queen and I" by Gym Class Heroes
On that note, browse through their other music and see if it's right. They've got a R&B/rock sound.
They're also currently popular, and I've heard stores playing them before.
Not necessarily The Gap, but....you get what I mean
I'm also going to say "Smiley Faces" by Gnarles Barkley.... I may be crazy, but there's this little voice in the back of my head telling me it was used in a Gap commercial. I could be just insane, though :blink:
Are you sure it wasn't Fatboy Slim? Something like "The Rockafeller Skank" maybe?
Here are a couple of other random songs that come to my mind:
"19-2000 (Soulchild Remix)" by The Gorillaz
"Dare" by The Gorillaz
"Cobrastyle" by The Teddybears
"Different Sound" by The Teddybears
"Seed (2.0)" by The Roots