他答应帮我修电脑，结果来了个调包计，把我的新零件换走了。

He promised to fix my computer but pulled a ___switcheroo and took my new parts instead.

趁我不注意时，他把我的新手机换成了一个模型，真是玩了个调包计。

He pulled a ___switcheroo and replaced my new phone with a dummy when I wasn't paying attention.