What is this expression mean?
"Thicker than water" is an idiom shortened from "blood is thicker than water". "Blood is thicker than water" means that there is a strong family bond. Basically, it means that your family is one of the most important things in your life. Thick blood is used as a metaphor to show that family bond is very strong. In this video, he is saying that brothers have strong bond and they care about each other.
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