Don't use ketchup on your hot dog after the age of 18. (We all have to grow up sometime)

"Nah, this stuff isn't getting to me, the shootings, the knifings, the beatings, old ladies being bashed in the head for their social security checks... Nah, that doesn't bother me. But you know what does bother me? You know what makes me really sick to my stomach? It's watching you stuff your face with those hotdogs. Nobody, I mean nobody puts ketchup on a hot dog." (Dirty Harry's famous speech about never putting ketchup on a hot dog)