One of the seminal episodes of the show that brings so much together. The easiest and slightest story is Barney discovering that the words "it's for the bride" are a kind of superpower that make people at weddings jump at your ever command. It's a solid comedic throughline for the character, and it works to a tee. But the main event is the massive logistical pain that is a wedding and all that can go wrong. Lily trying to keep her calm, and then losing her cool after almost anything that could go wrong does go wrong for a wedding that had already spiraled away from what she and Marshall wanted was well-observed in its take on the insanity and panic of these types of occasions. At the same time, Marshall's horrific haircut, and the array of poor choices he and the rest of the gang made in trying to cover it up was a hoot. And the end of it, "we thought of Indian headdress before we thought of hat" was the perfect tag to the storyline. Then, in the end, it all comes together in a beautiful ceremony that is, conveniently, just the five main characters. And it doubles down on the important thing in a wedding, the celebration of two people's love for one another. The vows from both Marshall and Lily reveal the affection and connection between them, as well as their shared sense of goofiness, that makes it all better and let's them have the wedding they want before the wedding they don't. It's one of the sweetest, most romantic moments on the show (and Barney's breakdown while performing the ceremony is kind of adorable in its own right), and works well as the affirmation of the kind of relationship the show has depicted Marshall and Lily as sharing for some time now. (Plus, the tag's "please don't" call back was the icing on the cake!)