Repeating the Original Funeral Service (Balkans)
Since a lot of the "mysterious deaths" blamed on vampirism were merely due to contagious disease, having everyone get together seems like the worst idea possible.
Lemon in the Mouth (Saxon Regions of Germany)
We think this would be more of a practical joke than a death blow. The vampire struggles to get the lemon out of its fangs while sour juice slowly drips onto its tongue.