A "Roberto" is slang for any infection incurred from sexual practice. This includes STD's, as well as infections from contact with fecal matter, from example.
He’s a guy named Roberto , he thinks he has a big dick and he has a fuckable face! He likes tacos and eats them everyday ! And he likes being called papi , and he’s Mexican and his grammar is really bad and needs to stop ditching class and thinking he’s cool