So, this is a really advanced joke — seriously, though, are there any farmers on the Iron Islands, or do you have to pay the iron price for vegetables, too?

I couldn’t help it — it’s because HBO made the “DO NOT” really big on their Greyjoy sigil, so I read it as meaning:

"We absolutely, indubitably DO NOT sow, metaphorically or literally and everything in between — and If we catch you sowing, you’re a dead motherfucker."

Also, y’know, if Theon can’t have it, no one can.