I'm going to tell my best friend her hair is ridiculous.
What don't you like about her hair?
I think it is way too long.
Maybe she likes the way that her hair looks. You should not insult her about things that make her happy. It can really hurt her self esteem.
I bet it's not even her hair and that she wears a wig.
Even if she does wear a wig, there is no reason to say that to her. You could hurt her feelings and make her feel bad. Why not focus on something you feel is positive about her appearance?