blonde agglutination
The social phenomenon where blonde girls clump together when in a large group setting. The lack of melanin in their hair is thought to be responsible for this chemotactic effect.
*two brunettes at a party*
"Do those girls know each other?"
"No, it's blonde agglutination.... they have no choice."
"Do those girls know each other?"
"No, it's blonde agglutination.... they have no choice."