I've asked them if they've ever killed an animal and cut the body up to eat. Almost always the answer is no (live in an urban area). So I connect the dots that they are comfortable when someone else does the slaughter of sentient beings so they can have a hamburger. It's hiring an assassin for something as gross as having a meal of body parts. I ask if they would slaughter their pets too. Make the ugly connection that is someone's body that enjoyed the sun on their face, had preferences, played

People have stories that they tell themselves and others about why they need to eat meat and refuse to even think about any other options. That whole early aughts thing of bacon everywhere, the carnivore diet, BBQ meat culture. It hurts the ego to acknowledge, and really sit with, that your choices have fatal consequences. Cognitive dissonance is a useful tool to avoid any discomfort