Gabby's Gold - S3-E8
Revealing mistake: When Kim and Gabby swing from the bar to kick the two villains, its obvious that Gabby kicked the guy in the knees, but he falls holding his chest. Plus Kim was a good 8-12 inches from her target and he fell anyway.
Answer: Because he was friends with Kim but he went to the same dojo as the other kids that's how he knows both Kim and the other kids.
No, it never said that. Maybe I'm mistaken, but she wasn't cool with anyone from Bobby Wasabi at the alleged time. So if she did know Carson it wasn't like they were friends, more like enemies if they did know each other.