Obviously you need to make a puking pumpkin this Halloween. My personal preference is to do the bare minimum with the pumpkin (does it have a mouth? does it have eyes? you're done.) and just throw on a whole bunch of Costco-brand guacamole, because come on: it's a vomiting pumpkin - how much more do you need?
But if you want to get all fancy and particular about it, here are a whole bunch more ideas for how to completely gross out your guests.