Billy's out here proving that zero is not an element of the natural numbers by committing what can only be described as mathematically justified homicide. The victim clearly thought 0 ∈ ℕ, which is a debate that's been splitting mathematicians into warring factions since forever. Some definitions of natural numbers start at 1 (the counting numbers), while others include 0 (the whole numbers starting from zero). Billy's taking the "natural numbers start at 1" stance and he's taking it very seriously. Fun fact: This isn't just pedantic nerd rage—it actually matters in set theory and computer science. ISO 80000-2 standard says natural numbers include zero, but plenty of mathematicians will die on the hill that ℕ = {1, 2, 3, ...}. Billy's just making that metaphor literal.