Ultimate Donkeypunch
A variation on the donkey punch in which, instead of merely striking the receiver, the dominant party snaps their neck 180 degrees, severing the spinal cord and causing death spasms -- with the added bonus that, mid-orgasm, they get to see the life fade from their partner's eyes.
So I ultimate donkeypunched her, but it's not necrophilia -- I pulled out before she went limp.