How much of a homophobic heterosexual man are you?
I'm a heterosexual man that is so homophobic I won't suck a big dick that has ketchup on it.
How much of a homophobic heterosexual man are you?
I'm a heterosexual man that is so homophobic I won't suck a big dick that has ketchup on it.
The joke plays on the stereotype of extreme homophobia by exaggerating it to an absurd degree. The punchline suggests that the man's homophobia is so intense that it extends to being disgusted by even the hypothetical idea of oral sex on a penis with ketchup, implying that the very idea of it is repulsive to him due to his assumed sexuality. It's funny because of the hyperbole and the unexpected specific detail.