screaming

My doctor swore that my colonoscopy would be painless, but the nurse made it seem otherwise. "The lab," she said, "will call you for your screaming."
オチが中々分からなくてやっと気が付いたのは "screaming" が "screening" の駄洒落と気が付きました。
"screen" のOneLook Quick Definitionでの説明です。
"screen": test or examine for the presence of disease or infection ("Screen the blood for the HIV virus")
やはり駄洒落のジョークはユーモアには負けますね。