The kids are gonna like me more, since I'm giving them bumps inside Parliaments, so they can also have a smoke with their coke. It's basically the same as giving out full-size candy bars. 😌
Sometimes on Halloween when families are out trick or treating themselves, they'll leave a bowl of candy out in front of their house with a sign that says something like "take one per child".
This is a play on that, but it's a bump of cocaine per child. You're supposed to snort it using the key.
Instead of a bowl of candy that kids would take one of on the night of Halloween, a US holiday, they are jokingly offering a small amount of a drug, likely cocaine, to the kids.