Picking out the perfect ugly Christmas sweater for a holiday party is easy.
The tricky part, as Ryan Reynolds just learned, is making sure that you're actually attending an ugly Christmas sweater party.
On Thursday night, the actor shared what happened when he failed to do that before arriving at a get together his pals threw.

Reynolds posted two photos on Instagram, and in both he can be seen sporting a gold bow-embellished pullover as he's flanked by his smiling friends, Hugh Jackman and Jake Gyllenhaal — neither of whom were dressed similarly for the festive occasion.
In the first shot, Jackman gives Reynolds a sympathetic pat on the shoulder while a beaming Gyllenhaal offers a thumbs up. Reynolds simply frowns.

"These (expletive) said it was a sweater party," the star fumed in the caption.
In the second pic, the pranksters reach to give each other a congratulatory handshake.
Reynolds? Still frowning.
The hilarious shots are just the latest evidence of the friendly war of pranks that been brewing between Reynolds and Jackman for years.
In fact, the "Deadpool" star was due for a little retaliation after he roasted Jackman last month with a mock political ad.
Although some might argue that Jackman — or at least his dog — already got him back.
We can't wait to see what's next!