Meaning:
"吹" is short for "吹捧," which means to "flatter" or "tout," and "黑," which literally means "black," is used as a verb "demean." Therefore, this term means to "neither flatter nor demean," ie., to evaluate someone or something objectively and fairly. The name of a talk show program about basketball on sports.qq.com, this term is widely used by young people nowadays. They would open a sentence with this catch phrase to emphasize that they are trying to be objective in a statement.
Example
A: 成龙拿到奥斯卡终身成就奖了。
Chénglóng nádào àosīkǎ zhōngshēn chéngjìu jiǎng le。
Jackie Chan received an honorary Oscar for his "extraordinary achievements" in film.
B: 不吹不黑，这个奖是他应得的。
Bùchuībùhēi, zhègè jiǎng shì tā yīngdé de。
Frankly, he totally deserves this award.
A: 同意。成龙是这四十年来把动作片和喜剧片融合得最完美的大师。
Tóngyì。Chénglóng shì zhè sìshí nián lái bǎ dòngzuòpiān hé xǐjùpiān rónghé de zuì wánměi de dàshī。
I agree. Chan is the best in 40 years who have merged action movies and comedies.
(Edited by Stephanie Yang)