It's a play on words. Shipping can mean putting people in a relation'ship'. thegestianpoet is saying to stop (relation)shipping real people (in your imaginations), but by adding "or at least poke holes in the box", turns it into stop shipping (sending/mailing something in a box to another location) real people without putting holes in the box so the real person doesn't die. You think it's for (relation)shipping but its for mail shipping. That's the joke.
someone explained above, but an example would be:
I shipped this box using Fedex.