Hand in Hand, her hand was stuck to Kick Buttowski's hand, and everybody think Kendall and Kick are boyfriend and girlfriend.
In Dancing with the Enemy, where they are paired as a dance group.
The third episode, Detained, is where Kendall begged about Kick being sent to the office. Her locker says a I heart KB before it got wiped by the janitor.
At times, Kick actually likes Kendall for her inner awesome personality like in Hand in Hand, and actually dreamed Kendall as a beautiful action-packed in his action dream in the episode Rocked.