What is the nuance of "come on" in this case?

Rebecca

"Come on" here is used to express disbelief or show that you don't think someone is being serious about something. It is similar to saying "yeah, right" in a sarcastic way. It can also be used in this way to express annoyance. It is usually said in a slow, sarcastic tone. Ex: Come on, you can't be serious, you're just being dramatic. Ex: Oh come on, it's not that bad, just try it!