Noun
manic pixie dream girl (plural manic pixie dream girls)
(film, sometimes derogatory) A stock female character, typically characterized as a bubbly, quirky free spirit, whose main purpose within a narrative is to teach a young male protagonist to embrace the mysteries and adventures of life. [from 2007]
Her best friend, Becca, is hanging out with Olivia, and Lexi is more comfortable hanging out with the cute Logan and his friends in a band, Manic Pixie Dream Girl, who want Lexi to sing with them. Source: Internet