If you’re a Miami Marlins fan, don’t believe the team’s latest Facebook post about giving away free pitbulls. The site was just one of several Major League Baseball team pages that was breached on Thursday. The unknown hacker gained access to the social-networking accounts of the Marlins, Cubs, White Sox, Yankees, Giants, Padres, and Nationals, posting fake messages about a Derek Jeter sex-change operation and derogatory comments about actor Bill Murray. The league is investigating the security breach.