Englishman, Irishman, Scotsman and the Toast

There was an Englishman, an Irishman, and a Scotsman stranded on an island. They see a cave up ahead.

The Englishman goes in and sees some toast on a rock. He goes over to it but then a voice comes.
"Dont eat the toast," the voice shouts.
The Englishman runs out.

The Scotsman walks in and sees the toast as well, the voice comes back.
"Don't eat the toast." The Scotsman thinks it's his imagination but then he hears it again,
"Don't eat the toast," says the voice,the Scotsman runs out.

The Irishman wondering what's going on, goes inside. He hears the voice once, thinks nothing of it. He hears the voice again, still he ignores it. He picks up the toast and eats it. The voice shouts,
"I warned you once, I warned you twice, I wiped my arse upon the slice."