Ted tries to keep Barney away from his sister who's in for a visit, while Marshall helps Robin with her homesickness about being away from Canada around Christmastime.
This episode provides examples of:
- Annoying Younger Sibling: How Ted sees Heather.
- Batman Gambit: Barney and Heather pretend to have sex so Lily will catch them and tell Ted, just so Heather can prove to her brother that he "
sucks for assuming the worst of her," despite him having all the right reasons to do so. - Bitch in Sheep's Clothing: The people at the Walleye Saloon are not so Minnesota Nice.
- Brick Joke: The "Canadians are afraid of the dark" gag.
- Broken Aesop: Heather wants to prove to Ted that she's now mature and responsible. That's a good thing. But staging with Barney that they had sex and allowing themselves to get caught by Lily so she can tell Ted, and once Ted confronts her about it, rubbing it in his face how "unforgiving" he is for her to do it? Not exactly helping. The fact that Ted ends up apologizing to her when all his misgivings were justified (Did she ever replace his TV?) just makes it all the more jarring, not to mention that Ted was starting to trust her before he thought she and Barney had slept together.
- Call-Back: Lily's inability to keep a secret was used by Heather in her Batman Gambit against Ted.
- Cannot Keep a Secret: While Lily is already known as this, this is especially bad around the holidays.
- Character Development:
- The episode establishes Marshall and Robin's friendship after spending the last three seasons as The Friends Who Never Hang.
- While she did a controversial way to prove it, Heather becomes more responsible.
- Christmas Episode: For Season 4.
- Continuity Nod:
- Ted mentions in Season 2 that he has a married sister.
- Barney mentions his alleged UST with Ted (and Heather)'s mom in "Brunch"
- Marshall sang "Let's Go To The Mall" in The Stinger. Robin also hid her face when he's doing it, backing up that she sees her past as a Teen Idol as an Old Shame.
- Courteous Canadian: At The Hoser Hut, Marshall is amazed that people there are even nicer than the people at the Walleye Saloon. If you bump into a stranger, that person is the one who apologizes, and even offers you a donut.
- Family-Friendly Stripper: Mentioned when Robin is defending Canada and, correctly, points out that her country doesn't have the same laws as the US that ban serving alcohol in fully-nude strip clubs.Robin: From Moose Jaw to the Bay of Fundy, you can suck down a 20-ounce Pilsner while watching some coal miner's daughter strip down to her pelt. Jealous?
- Foolish Sibling, Responsible Sibling: Ted lists Heather's shenanigans to the gang which includes getting married for a brief time, selling stuff at the apartment to go to a Pearl Jam concert in Spain, and taking too long to graduate college.
- Former Teen Rebel: Heather is quite a headache to the Mosby family.
- Hostile Show Takeover: Robin integrates herself in Marshall's crowd by copying his old stories. Marshall retaliated in response by exposing her.
- Hypocrite: The people at the Walleye Saloon antagonize non-Minnesotans despite the bar being in New York, meaning they're technically outsiders as well.
- Intercourse with You: Barney altered some Christmas songs lyrics to lewd ones to show how much he lusts for Ted's sister Heather.Barney: (In tune of Jingle Bells) Pulling down her parts. Yanking off my own. Underneath the mistletoe, I'll make your sister moan. Oh! Heather's hot! Heather's hot! We'll go all the way!Barney: (In tune of We Wish You a Merry Christmas) I wish I could see her naked, I wish I could see her naked, I wish I could see her naked! And down on all fours!Barney: (In tune of I Have a Little Dreidel) Ted has a little sister, gets hotter every day. And if I ever meet her, with her boobies I will play! Everybody! Sister, sister, sister...!
- Jerkass Realization: Marshall realizes how douche-y he was to Robin when he revealed to the bar that she's Canadian.
- Local Hangout: It's revealed that whenever Marshall's homesick he goes to a Minnesota-themed bar called the Walleye Saloon where he and his fellow Minnesota expats can enjoy drinks, food, and entertainment they'd typically find back home. Near the end of the episode, Marshall finds The Hoser Hut (a Canadian themed hangout) to make up to Robin.
- My Sister Is Off-Limits: The episode's premise. It involves Ted being very uncomfortable at Barney hitting on his sister. However, it turns out Barney had no intention of actually doing anything with his sister and was just trolling him.
- Not What It Looks Like: Heather and Barney deliberately made it look like this to Lily so she'd tell Ted.
- Only a Flesh Wound: One of Marshall's friends at the bar mentions he tore a ligament in his knee while playing pickup hockey. Rather than go to the hospital and miss the Vikings game on TV, he just poured some cold beer on it.
- Patriotic Fervor: Once her being Canadian is exposed, Robin proudly stood up for Canada.
- The Place: The Walleye Saloon, the Minnesota-themed bar where Marshall takes Robin.
- Politically Incorrect Hero: The people at the Walleye Saloon have prejudice against people from other states, especially Canadians.
- Shout-Out:
- Barney's altered Christmas songs above.
- Ted calls him the Weird Al Yankovic of Christmas songs about nailing his sister.
- Vikings jerseys worn in the Minnesota-themed bar bear the last names of series star Cobie Smulders, episode writer Chuck Tatham, episode director Pamela Fryman, and series co-creators Carter Bays and Craig Thomas.
- Marshall is wearing a #70 Minnesota Vikings Number. Number 70 was in honor of retired Jim Marshall.
- When Marshall is singing "Let's Go To The Mall", Robin hid her face in a Jason mask.
- Barney's altered Christmas songs above.
- What Happened to the Mouse?: After this episode, Heather never appeared on-screen again. Though she is mentioned as being present at Ted's mother's wedding.
