The song is "Writings on the wall" by the Norwegian progressive rock/metal band Green Carnation.
Revenge. It's like saying "Well, you shouldn't have fucked with me, sir. Now you'll see why was fucking with me such a bad idea. You won't fuck with me again, I assure you." But why do it? Isn't revenge a petty, childish act, a result of needing to show someone you are actually worth something? The use of your energy trying to teach someone a lesson, who obviously doesn't deserve to be taught a lesson? Yes, all that. But it's fun. The sole thought process is cathartic. The execution is psychotherapeutic. But most of all - it's pure, primitive fun. It's our way to enforce biblical justice. You messed with me? Prepare to be über-pwned!