Final answer:
In 'The Office' Season 3, Episode 20, 'Product Recall', Michael assigns Andy Bernard to train the Accounting department in customer service, which angers Angela.
Step-by-step explanation:
In S3E20 "Product Recall" of The Office, Michael assigns Andy Bernard to train the Accounting department in customer service. Angela, who is part of the Accounting department, is displeased with this decision. Angela's chagrin is likely due to her personality clash with Andy and her general disdain for non-traditional approaches to her work in accounting.
Andy's often over-the-top behavior and eagerness to please may have been the reasons why Michael chose him, but they also serve as potential sources of frustration for Angela.