If this hadn't been the first class, Sam wouldn't have taken anything and just tried to use his necromancing abilities to control the zombies. But, since this was the first class and he wasn't really into freaking people out so soon, he grabbed a tire iron and took it with him into the bathroom. It would probably work better than a wooden skateboard, at least.

He slipped into a stall quietly and crouched on top of the toilet seat, holding the tire iron. When everything seemed quiet, he reached back and flushed which he knew was noise enough to draw attention.

Sure enough, Sam heard something trudging into the bathroom and waited until the feet of the zombie was right in front of his stall before he kicked the door open and knocked the zombie back allowing him time to get out of there. He didn't wash his hands.