GAZA CITY, Gaza Strip — In back rooms and refugee camps across this impoverished territory, young men are rapping over hip hop beats, flipping over metal bars and spinning on their heads to funky dance music — not the preferred hobbies of Gaza's Hamas rulers.Many youths, who make up the majority of Gaza's 1.5 million residents, are stuck between Hamas' strict version of Islam and an Israeli-Egyptian blockade that keeps them locked in with little work.Inside, however, creativity blooms, sometimes clashing with traditional Gaza social codes or Hamas' standards of acceptable behavior.Rap, for one, raises suspicion."When we started, everyone said, 'Why are they wearing baggy clothes? Why do they greet each other like that?'" said Ayman Mghamis, 25, of Palestinian Rapperz, one of Gaza's 10 or so rap groups.Gazans started accepting them, he said, but the Hamas government didn't.Hamas police broke up a show in March that contained a rap act. Police said the event lacked permits, but the rappers took it as a cue to keep their heads down. While underground, the rappers distribute songs on the Internet and perform at events organized by international organizations, which they say keeps authorities at bay. Other pastimes face different obstacles. A few times a week, four guys sneak into an elementary school to flip over metal railings, leap down staircases and launch their bodies off walls and tree trunks. They are one of at least two Gaza groups that practice parkour, the acrobatic art of using the human body to overcome obstacles.Their neighbors sometimes report them to the police."They see you climbing on a roof and they think you're a thief," said Mohammed Irgayig, 19.Like most of the rappers — and like most Gaza youth — all four are unemployed."I do it to get my head out of the situation I'm in and feel free," Irgayig said.Underground activities are rare for Gaza women, who have greater housekeeping duties and are expected to be discreet in public.In a small apartment, the nine male members of Gaza's premier break dance troupe took turns spinning on their backs, shoulders and heads, then flipping up and dancing on their hands.Mohammed Ghreis, 23, started the Camps Breakerz in 2004. They learn new moves from the Internet. Gaza has at least one other break dance posse, and Ghreis expects it to spread through children's workshops his group holds.Recently, two teens he didn't know showed up for practice and said they'd been teaching themselves from videos on the group's website.Ghreis played some music and gave them the floor."They were good," he said, beaming. "I was really proud."