Why does the Keijo anime/manga title have eight "!" characters?
Exclamation points in anime/manga titles is somewhat of an ongoing trend, and because of the ludicrous themes in keijo!!!!!!!! they jumped on the trend in a similarly extreme way as a sort of publicity stunt/way to attract attention. Some more toned back shows may use it to denote seasons (like K-ON!!) but for shows like keijo!!!!!!!! they are instead used to show a self aware, extreme and ridiculous nature.