Death of a Salesmen.
That's it.
I hated it. Sorry to anyone who may have liked it. Actually, I just found it really hard to get into plays at all.
Not at HS, but the worst text I've read at undergrad is Waiting for Godot. Love Joyce, I was just confused by Beckett.
I studied Death of a Salesman at HS and Uni, I think I understood it better at UG, maybe because it was a module on Tragedy. That's why I think so many youngsters get turned off classics, they don't have a decent grasp of what is going on.