I vote the following chain of events:

1) Staying in her ass (my penis serves as a buttplug, preventing the girl from shitting herself), I stretch out her nipples and then nail them to a nightstand by the bed.

2) I use a saw to slowly debreast her. The pain makes her ass tighten in a most pleasurable manner.

3) I don't let her die until after I cum. Maybe I'll cut out her cunt and then gut her through the hole where her pussy was?