There are many unwritten rules in sports about the etiquette between athletes. Usually, combat sports fighters touch the gloves of their opponent before engaging. It’s a sign of respect but sometimes people try to trick their rivals. Kassem did this in a UFC bout against Kim as she faked a glove touch. Kim acknowledged it but then Kassem sucker-kicked her in the ribs.
But it didn’t work out for the Australian because Kim immediately dropped her with a punch. Later, she suffered a TKO loss but the main damage was to her reputation. Many fans criticized her bad sportsmanship because they thought she was very disrespectful. Nobody likes seeing stars break the code of conduct in the cage (via The Sun).