Family Circus: I hope my dream tonight don't turn out to be a rerun.

And so it turns out that Jeffy's mind is so deficient that it is literally incapable of producing more than five dreams, which it just replays over and over again in a randomized loop. Given the lack of wish fulfillment in Jeffy's sleep, it's no wonder that he kills. He just wants to feel something, even if it's just the warm spattering of blood on his cheek.