In "Hefty Shades of Gray", Kristen asked out Chris to the prom, but he loudly rejected her. Stewie and Brian were surprised that Chris did this and wondered why he would do such a thing. After gay testing him, it came about that he simply just did not find her hot enough because his expectations were set way too high, by unrealistic internet porn.
Stewie and Brian prepare Chris to actually get himself attracted to Kristen. When he did, he went out with her to prom. Right when they were leaving, Kristen stated that she was not going to thrill kill him later. Later, in the newspaper, one of the stories was about a teenager getting thrill killed by a bunch of teenagers. This was totally Chris getting thrill killed by Kristen.