 At home , Homer reprimands Lisa for ruining his party and demands an apology , but Lisa refuses to apologize and chews him out for serving a meat @-@ based dish . They fight and she leaves the house , not wanting to live in a house with a " prehistoric carnivore . " As Lisa walks along , she decides that she can no longer fight the pressure to eat meat , prompting her to grab a hot dog from the grill at the Kwik @-@ E @-@ Mart and take a bite . However , Apu , himself a vegan , reveals that she has eaten a tofu dog , which he subtly switched out and none of his loyal customers had noticed the change . 
