When XXL caught up with Bun B on the phone, he was exiting his hip-hop and religion class that he jointly teaches on Tuesdays and Thursdays with Dr. Anthony Penn at Rice University. Perhaps due to the immense respect he’s earned as an iconic figure in the Houston rap scene, Bun’s students refer to him with esteem as “Professor Freeman” while in class. It's fitting that a figure who raps with such authoritative punch as Bun is deferred such an honorific title as “Professor” in an era when college students regularly address tenured faculty by their first name.

It also makes sense that a man as skilled at storytelling as Bun B would end up a respected teacher. Twenty-one years in a game as crazy as hip-hop will give you the authority to pass on the type of yarns from which a younger generation of hip-hop fans can learn. After a career that started at 19 when his legendary rap group UGK signed a five-album deal with Jive Records, Bun B has been fortunate enough to have enjoyed the type of career that is tall with a poignant tale or two.

With his fourth solo album, The Epilogue, set to be released next month and a new coloring book out in stores now, Bun is enjoying a hell of a career renaissance for a rapper entering his fourth decade on the planet. Professor Freeman took the time out of his busy schedule to break down the stories behind some of his most iconic verses over his 21-year career. Read on to find out why he hung up on one of rap’s greatest MCs and why one of his raunchiest songs will probably continue to embarrass his grandchildren for years. —B.J. Steiner (@DocZeus)