A restaurant owner was caught on camera unleashing an angry rant on a customer after they did not leave a tip.
The heated showdown took place outside the ramen shop Table to Stix in downtown Evanston on Sunday, April 19, when the unidentified customer left a $20 bill to cover his $19.89 meal, leaving no tip.
Owner Kenny Chou was filmed following a regular customer - who allegedly doesn't usually tip for his meal - out into the street to confront them.
Chou was filmed calling the customer a "piece of s**t" and when the man asked why he was following him, Chou replied "18 percent", referencing the amount of tip he expected the man to leave.
The customer then says: "I paid for my food. I handed you $20. You cannot charge more than what you paid, so what are you talking about?
"What do you want? I paid for my food!"
As the clip continues, the man tells Chou to "get the f**k back" and call the police if he wishes to escalate the situation, adding: "I paid for my food. I paid you $20. I am not legally required to give you a f**king tip."
Chou then shouts: "I’ll smack the s**t out of you, you punka** s**thead.
"Shut your goddam f**king mouth. How are my staff supposed to make money? I’ll slap the s**t out of you!"
Online, the restaurant had stated that tipping is optional - and in most cases, people usually tip if the service they have received is exceptional.
Tipping culture also varies around the world, with the US expecting customers to usually leave a gratuity, while other countries only leave tips when the staff really go over and above for the customer.
After the incident went viral, Table to Stix - which had previously had overwhelmingly positive reviews praising the food and atmosphere - was hit with a flood of bad reviews regarding the video.
Chou spoke out on Saturday to address the incident and apologize, claiming his frustration stemmed from the business struggling.
He told a protest gathered outside the restaurant: "It was a deeply regrettable moment where I, Kenny Chou, lost my composure.
"I stepped far beyond the bounds of respect and decency."
Chou also tried to make amends by sending the customer's brother his favorite meal free of charge along with a handwritten apology.
He told CBS News Chicago: "I apologize to him and to his family, and I was just asking if he could pass this message along to his little brother."
When asked why he didn't tip, the customer who filmed the video simply responded: "Oh, I just didn't want to."
Evanston Police Department confirmed that an investigation into harassment is ongoing.