In the world of Westeros it's hard to believe that anyone would dare mess with the North. I mean seriously, have you met Lady Mormont? Arya Stark? Jon Snow? *Spoiler alert* but he totally destroyed Ramsay Bolton. And I don't know about you but I totally think deep down Cersei knew not to mess with the Starks but she just couldn't keep her damn son from beheading Ned. Worst thing they could've done, cause the North Remembers. 

And if you want to intimidate your friends, just wear this 100% cotton Game of Thrones North Remembers Men's T-Shirt! That, and, you can memorize the Lady Mormont speech....