The Short Version
Berlusconi did publicly target Rosy Bindi with derogatory remarks, most notably the well-documented "più bella che intelligente" quip on the nationally televised program Porta a Porta in 2009. Whether this constitutes a "joke" depends on definition — the best-sourced evidence describes it as a sardonic insult or quip rather than a traditional joke. Separate, lower-authority sources also document Berlusconi telling a joke specifically about Bindi at a public event in Abruzzo, providing additional corroboration.