The word Boo is often used as a term of affection; it typically refers to a boyfriend or girlfriend.
So when a girl refers to you as her Boo, she is saying that you two are romantically linked; you are her boyfriend.
Some other terms a girl might use include:
- • Baby
- • Better half
- • Daddy
- • Hunny
- • Main Squeeze
- • Ol' man
- • Pookie
- • Sweetie
EnStarz.com reports that Khloe Kardashian is getting more serious "with her new boo, French Montana." This is causing some friction in the Kardashian family because Kim doesn't want him to attend her wedding to Kanye West, stating that Montana is just "some random guy."