Insulting or ridiculing customers is bad for food service workers.

A Coral Springs, Florida restaurant employee learned this back in February after writing a three-letter word on the receipt of a police officer who ordered a takeout lunch.

When the officer confronted the cop-hating cashier for the insult, the latter "reiterated his disdain for law enforcement," Coralspringstalk.com reported.

The local police union complained to the restaurant about the staff who wrote "PIG" on the officer's receipt and the management responded by firing the worker.

The incident did not teach a lesson to a barista of a Starbucks outlet in an Annapolis, Maryland shopping mall nine months later.

Customer Monique Pugh recounted her trauma from the coffee shop's staff when she ordered a venti caramel frappuccino last month.

Recalling the incident, Pugh told NBC News that she used the Starbucks app to pay her order and verbally told the woman cashier her name.

However, Pugh was bothered after her order, instead of her name, was called for her to pick it up from the counter after other customers' names were announced.

When she saw the label on her cup, Pugh felt embarrassed and immediately complained to the cafe staff and manager.

"Why am I the only Black person in the store and 'monkey' is written on my cup?" Pugh said, according to NBC News.

Recounting her experience on social media, Pugh said she did not receive an apology, only a refund, that day. The management of the cafe's franchisee, Impeccable Brands, and a representative of Starbucks later reached out to Pugh to inform her that the responsible white barista was suspended and made to attend the company's anti-bias training.

Amit Sehgal from Impeccable Brands apologized and said that the word "monkey" has been removed from the Starbucks order-naming system to prevent a repeat of the incident.

Pugh was also offered a free drink and sandwich from Starbucks which she called disrespectful and rejected.