Can't find how Lerpz punches Copper

I'm going through the Lerpz tutorial and I can't find the instructions for how to make Lerpz punch the Copper.

And what Key would that be? Makes sense to tell us, since this is in the google search results huh

Found this on Google: Controls

W / Up Arrow - Move Forward S / Down Arrow - Move Backward A / Left Arrow - Move Left D / Right Arrow - Move Right Spacebar - Jump/Use Jet Pack. Hold the spacebar to control your descent with the jet pack. Mouse Left Click - Punch Mouse Right Click - Center camera at Lerpz's forward view