Equipped with metal tools and engineering know-how, three students crept late one night into the Faculty Club at the Massachusetts Institute of Technology. They pried open a wall panel, gaining access to crawl spaces in the ceiling and walls. And then the alarm sounded. The intruders that October night were participating, they say, in a time-honored tradition of elaborate pranks at the tech-savvy university. In most contexts, such pranks could be considered criminal, but at MIT they are called hacks and are cause for celebrating student ingenuity. Offending students have rarely received any punishment sterner than small fines or community service. But in this case, the three students face up to 20 years in prison if they are convicted of felony charges of breaking and entering and trespassing.