This is from “Amino-X” [kj5nh@arrl.net] who posted it on PUNY.

A rather harried and frazzled woman arrived at an airport one day struggling with a dilapidated old suitcase made entirely of styrofoam. It was barely in one piece and covered with duct-tape to hold together what little of it was left.

Seeing this, a security guard went over to help the poor lady with her things. As they walked to her gate, he asked casually, “Madam, if I may ask, why are you carrying your things in this horrible old styrofoam suitcase?”

She looked at him and kinda smiled as she replied, “Even though it may crumble, there’s no case like foam.”