Two's Company Clifford the Big Red Dog : Season 1 Episode 73

All of the dogs are so excited that their old friend K.C. is back on the island for a couple of days. Cleo, however, is particularly excited and focuses all of her attention on him – at the expense of ignoring T-bone and Clifford. She discovers that being a good friend means you should be kind and considerate to all your friends and not take any of them for granted.