The so-called "spring slang" is a type of secret jargon commonly used among various underworld factions, with the Eight Hidden Gates using it the most to easily pass messages. Before entering Shrek Academy, Huo Yuhao often had to deal with people from all walks of life, so naturally he knew the slang. Of course, he only started learning it after getting burned a few times.
You live and learn, after all.
The two people Huo Yuhao noticed were speaking in spring slang, meaning he had spotted a bald man, specifically the one with a towel draped over his shoulder. Mingshan referred to drinking, and the term "tooth-seller" meant a human trafficker.
Chapter 472