CRUNCHBASE – Nov 25 - F3, a new social app aimed at Generation Z, has raised a $3.9M seed round led by the Mamba dating network. The app lets users send each other questions, photos, and videos, and reply to each other's posts. The app allows users to reply to posts anonymously. The founding team of F3 was also behind the social networking site Ask.Fm, and the idea for F3 was inspired by Ask.Fm, according to co-founder, Girts Tihomirovs. F3 has ~25M registered users on the app, with ~85% of them under the age of 25. The company's target audience is in Europe, with about half of its users there, with 20% in South America, and 20% elsewhere.