How I Met Your Mother season 9 spoilers Find out what happened during episode 21 of "How I Met Your Mother" tonight. Photo: How I Met Your Mother

Only one episode remains until “How I Met Your Mother” airs its highly anticipated series finale on March 31. And you know what that means, right? It's almost time to say goodbye to our favorite gang. But fans won’t be waving farewell only to Ted, Robin, Barney, Marshall and Lily; they’ll also be saying sayonara to all the fabulous guest stars who’ve made us laugh throughout the hit CBS show’s nine-season run. And that’s exactly what fans were able to do in episode 21, “Gary Blauman.”

Monday night’s episode began three days after Robin and Barney’s wedding, with Ted picking up the Mother on their very first date.

“So, I thought we’d try a new restaurant that’s right around the corner from here,” Ted said to his future wife. “It’s Scottish-Mexican fusion.”

“Scottish-Mexican fusion?” the Mother questioned Ted’s taste in food. “That seems like two things that do not fuse.”

“Perhaps you’ll change your mind when you try their signature haggis enchilada,” he quipped.

On their way to eat some oddly paired dishes, Cristin Milioti’s character confessed to Ted that she was surprised how quickly he asked her out. “Isn’t there some guy rule where you have to wait four days to call a girl?” she questioned. Ted revealed that he waited three days to call his future wife.

With that said, the duo arrived at the restaurant, where they were greeted with a blaring mariachi band.

“I did not realize there would be live music,” Ted said, obviously embarrassed.

“So, should we…” the Mother said only to have Ted finish her sentence, “eat anywhere but here?”

“Yeah!" the Mother replied. “Besides, I’m sure we can find a place where we don’t need reservations.”

“Oh, you think it’s just that easy?” Ted asked. “Just stroll in off the street and get a meal? Well, let me tell you the tale of Gary Blauman.”

Episode 21 dives into the story of Blauman and the gang's last encounters with Marshall and Barney’s former co-worker  — starting with Robin.

Blauman spots Robin and sweetly congratulates her on the big day. And as soon as he leaves, Robin sees Marshall and totally freaks out.

“Code red!” she said, adding that Blauman’s RSVP must have gotten lost in the mail. Robin began panicking over where her unaccounted-for guest would sit. Cool as a cucumber, Marshall calmed the blushing bride down saying he would handle the situation. But that was a blatant lie.

“Code red!” Marshall screamed at Ted, telling him the dilemma.  

“Did you just say Gary Blauman?” Ted asked. He then dove into the story of why he “hates” the Theodore Roosevelt-loving lad. Apparently, Blauman tried to steal a girl away from Ted during his own party. “Let’s send Gary Blauman packing.”

“Did you just say Gary Blauman?” Lily said, overhearing the end of the conversation. “I love that guy! It was 2006, Marshall and I had just broken up and I was back in New York feeling vulnerable. I hit bottom.” And boy did she ever. Lily ended up getting a butterfly tattoo during her depressed stage. “Gary saw me, dragged me out and talked some sense into me.” Lily confessed she was this close to getting more than just a butterfly. Picture Sugar Ray surrounded by fluttering bugs.

Just then, “HIMYM” cuts to Ted and the Mother’s first date. She pulls him behind a truck in hopes of hiding from her ex-boyfriend, who she had just turned down a proposal from a few days prior.

“I really like you, but I’m in the weirdest place on Earth. It’s too soon for me to be dating. I think I’m going to walk home,” she said.

Being the gentlemen he is, Ted asks if he can walk her back — and of course, finish the story.

“Did you say Gary Blauman?” Barney asked the gang. The groom told his tale of how his former co-worker stole his fries — including an accidentally curler — and that’s why he doesn’t want Blauman at his wedding.

William Zabka then chimed in saying he loved Blauman because he was the first person to recognize him as a poet. But that wasn’t the weirdest part of the story. Barney’s brother James that admitted Blauman was the one he cheated on Tom with.

“Wait, Gary Blauman is gay?” Ted questioned. He then cheered himself up saying Blauman must have been flirting with him, not the girl!

Marshall decided in the end that Blauman should be allowed to stay at the wedding considering it was Robin’s wish. But Barney had already told his French fry thieving co-worker that he needed to beat it.

The gang ran out into the parking lot to stop Blauman from leaving, but he had already made up his mind to head out. “Take a good look: This face, you won’t be seeing again.”

Marshall said Blauman was right. He hadn’t seen his wedding attendees since the day he got married.

“The friends, neighbors, drinking buddies, partners in crime you love when you’re young—as years go by, you lose touch,” future Ted said.

The end of episode 21 gave fans a peek at what had happened to several of the gang’s acquaintances from MacLaren’s bartender to Blah Blah (whose name we found out was Carol). We even found out that Ted’s crazy ex-girlfriend married Robin’s former boyfriend Kevin!

But nothing warmed our hearts quite like when Ted finished his story. The Mother leaned in for a kiss goodnight and even asked her future husband to walk with her a bit.

“What are you doing?” she asked as Ted stood behind staring at her.

“Remembering this,” he said.

What did you think of tonight’s episode of “How I Met Your Mother”? Tell us what guest star character you loved hearing about the most! Was it Rashid, Patrice or even Scooter? Let us hear your thoughts in the comments section.