I used to love to pretend scare our dog. Just walk very slowly while staring, preferably with arms in the air and hands like claws, and in a deep low voice “I am... coming... to get... youuuu...”
Looks like a martingale, or rather the collar part of a martingale. That's a kind of slip lead with two loops, the smaller one tightens the larger one through a pair of D-rings.