1. Make your way to the bonus located near the upper left of the halfway barrel.
2. Throw Diddy or Dixie above the bonus and hold to the left for a while.
3. You will then fall behind the bonus cave and into the honey. You can't do much, but it's pretty unique.

I find it strange that Imageshack still has that picture hosted up; It's been on their servers since April 2006.