I gave my friend a disgusting treat and they enjoyed it, it just confirms that they are crazy.
What if your friend doesn't find it disgusting?
Doesn't matter, it's still confirmation that he is crazy.
They're not crazy because they like something you find gross. It's fine to agree on disagreeing, though.
Whatever you say kill joy, my friend is crazy for liking cookies.
You're being hypercritical about this. A lot of people have different tastes when it comes to food. Liking something that others may not like doesn't make you crazy, it's just a simple difference in taste.