Just the fact that she's John Cassidy's (from Fallout 2) daughter won me over, but beyond that Rose of Sharon "Cass" Cassidy is a fun companion with great voice acting and dialogue that I repeat still to this day,
Cassidy is arguably one of the best companions you can travel with in Fallout 2 for combat, especially if you give him a Gauss rifle. The hardened wasteland veteran that got old and settled down as a bartender in Vault City unless you go there and ask him to join you. The con is his prejudice against Lenny the ghoul, another companion you can travel with, and will insult Lenny if you travel with both at once. The pro is he also hates Myron, the sadistic drug supplier/slaver/sex predator, and Cass will endlessly insult him if you end up recruiting Myron to travel with both of you.
I imagine there would be other complications long before you started gagging.
I mean just the idea that anything could reverse navigate the labyrinthian maze of the typical human intestines would already be a feat of brobdingnagian cocksmanship.
But then you have to take into account the stomach acids and all of the things that were in the way long before you made it far enough of the back of the esophagus to trigger the gag reflex.
It's a level of sexual grotesquery that the most brain-rotted deviant furry on the planet couldn't even begin to contemplate.
I highly recommend the Tale of Two Wastelands mod if you also have Fallout 3. It combines 3 and New Vegas into one game and provides several bugfixes and improvements for both. It makes 3 worth playing again while also improving NV.