So, when a Reddit user asked, "What's the most passive-aggressive thing you can bring to a Thanksgiving dinner?" people were ready to share the hilariously petty "this is war" side dishes, holiday gifts, or other unwelcomed and gloriously vindictive surprises. Apologies in advance to your mother-in-laws...
A second turkey - Eternal_Bagel
A second turkey wins but also cleaning products, and then start quietly cleaning the host's house. My grandmother did both of these things! - piranha_moat
I had a family member who always brought a pie or casserole with a piece cut out already. Luckily, she was a sh*tty cook so I didn’t care that much. Still pretty rude. - ConfusionNext7704
Find out whatever dessert is being made. Then bring a professionally made/better version of it. Passive aggressive without being the weirdo who brought a whole second turkey. Plus it's normal to bring a dessert or side dish as a guest. - RudeReindeer2934