not a song lyric screw-up,but a screww up of almighty proportions.

Trying to explain to my senior history class about a moment in British History when the parliamnet refused to extend voting reform to one class, as this would open the floodgates to all groups demanding the franchise. I decided to use the metaphor of the little dutch boy who, obeying his parents, stems the leak in the sea wall by sticking his finger in the leak.
Unfotunately
1) the present generation of children no longer seem to learn such stories as children.
2) when I was a child, a dyke was a sea wall, nothing else.

So imagine the expression on the senior students faces when I absentmindedly and in all innocence announced,
   "It's just like the little dutch boy who spends all night with his finger up a dyke!"