The "19 hot" could signify the 19th edition or version of this guide, with "hot" implying that it's particularly relevant or popular among students seeking to elevate their academic performance.
The song is a humorous and linguistically clever exploration of physical and emotional proximity, utilizing medical and scientific terminology to describe attraction—a signature style of Wartke's "cabaret" entertainment. bodo wartke 90 grad noten pdf 19 hot
If you actually have the file and want to share it helpfully (without piracy – Bodo Wartke is an independent artist, so please support him), you could write: The "19 hot" could signify the 19th edition