http://www.bloggerpunit.com/what-does-tbh-mean-tbh-rate-date/

Nowadays, TBH has become a very popular term. Forget other social networks; you will find billions of posts with the #TBH if you search on Facebook alone. People are widely using it in chats, messages or texts to partners, friends, colleagues or any person with whom you want to get closer. It is helpful in expressing something you honestly feel. Using, To be honest, is lengthy and has now become old-fashioned, while TBH is short and sounds stylish as well.