I'll take this question seriously. While it won't matter to you, buckshot or even birdshot is the way to go with something like that. I'm no firearms expert but I have a more-than-the-average-person understanding of them. Essentially, all a slug is going to do is ensure maximum penetration of everything it's pointed at. This means an increased danger to anything behind the intended target. Buckshot means the kinetic energy is spread out significantly to each individual pellet, and birdshot further spreads it out, meaning far less over penetration once it leaves the barrel. Point blank with a shotgun round of any kind will go through whatever it's pressed against. In the interest of full disclosure though, it's probably one of the worst ways you can go, and not worth it in my personal opinion.