There's always the fun that ends up happening after a party of four (levels 2, 2, 2, 3) decides to feed the starving vampire spawn without doing anything as wise as restraining it. One of them held his arm above the vampire's mouth, then cut into it with a knife.

The vampire spawn, being cowardly, did not want to attack a larger group, however, when someone practically presents themselves as food like that, it turns out that vampire spawn do bite the arm that feeds it.

ten rounds of combat or so later and all but one were dead or dying. That one had wizened up and ran away, barricading the trapdoor down into the cellar the others were in.