In order to set up the gag, you need some background information.
One of their ads features a couple of bored guys in an Indian call centre. Watch the clip here, and you’ll understand why I was haunted by the very catchy tune.
I showed the site to the guys at work, and my brother tracked down the song. It’s called Numa Numa, and was a big hit in Moldova, and has since done the rounds of the internet with various people lip synching to it. Check out the Wikipedia entry here.
PS. The song is actually called “Dragostea din Tei”, by O-Zone.