Two can keep a secret if one of them is dead

Got a secret
Can you keep it?
Swear this one you'll save
Better lock it, in your pocket
Taking this one to the grave
If I show you then I know you
Won't tell what I said
Cause two can keep a secret
If one of them is dead,

Why do you smile
Like you've been told a secret
Now you're telling lies
Cause you have sworn to keep it
But no one keeps a secret
No one keeps a secret

You swore you'd never tell