Quick Altitude Loss

Hi All,
I was just watching a video about flying the Ercoupe, learning while I am waiting to rejuvenate my project plane. The host of the video mentioned something that sounded like a slip you’d do in a conventional aircraft to lose some altitude, but didn’t really go into it. He stated you turn the ailerons 20 deg while pulling back on the yoke. Does anyone have experience doing that? Can you describe how the Ercoupe behaves when it’s done? Is it effective, and safe? 
Thanks,
Shawn