Students at La Sapienza University of Rome knew him as Professor Freddi.
What they didn't know until recently was that their maths teacher was previously known as Carlos Masi, a popular gay porn star.
Ruggero Freddi's X-rated past resurfaced after he posted a video of himself flexing his muscles on Facebook and someone recognised him and contacted a local reporter.
He told Republica that he isn't upset that his past life has been uncovered, saying he wasn't hiding it.
"Some students reposted the photo in a few sites and from there my former life as a porn actor emerged," he explained. "To be honest, it wasn't exactly a secret."