This group of sweet adorable little trick or treaters are receiving a copy of Humbug magazine, a satirical publication in the late 1950s.
HUMBUG magazine was the joint effort of Harvey Kurtzman, Will Elder, and Jack Davis (who did the above art). They and a few others started their own magazine with a boss to dictate to them what should be in the magazine. They had the freedom to publish what they wanted.
HUMBUG lasted about a year or so and crashed.