The Fishkin Twins will play with absolutely any toy you put in front of them, but the one they love the most is this pom-pom pictured below. The ball is attached to a wand with a bouncy wire, and when you wiggle it, it moves in an unpredictable manner, so it's really fun to try to catch.
Once they do catch it, they sink their teeth into that pom-pom and hold on with all of their kitten might! If anyone comes near, there are growls that are both ferocious and ridiculous.
You're a silly kitten, Sid Fishkin.