The guards will betray you
And I will replace you.

The story:

I play bass (and sometimes sing, though not on this tune) in a
band, and we wanted to cover the song as part of a James Bond-
themed medley. I'd only heard the song in Casino Royale before
they showed it to me, but I liked it and listened to it a few more
times to get the bass part in my head.

After we were done with the run-through, our guitarist (who
sings it for us) was singing the tune acapella to himself and I
joined in. When I got to that line I obviously got it wrong, and
the rest of the guys had a good laugh. However, given that it
was a Bond themesong, the notion of the guards betraying you
seemed perfectly plausible.