His name is for sure revealed when the Lorax and the other animals in the Truffula Forest try to save him. He also loves Truffula Fruits and chose to grab a fruit instead of the Lorax.
A barbaloot resembling Pip appeared on Page 10 of the original Lorax book , marking a cameo. He loves the Once-ler, as a friend as they bonded during Once-ler's estance through the valley. Pipsqueak really seemed to like the company of the Once-ler.