Ted: MacLaren's Bar, four years ago...
[flashback to MacLaren's four years ago. Ted and Barney are both wearing tuxedos:]
Barney: How do you keep a girl from becoming your girlfriend? Simple, the rules for girls are the same as the rules for gremlins.
Ted: Gremlins?
Barney: Gremlins. Rule number 1, never get them wet. In other words, don't let her take a shower at your place. Number 2, keep them away from sunlight. I.e., don't ever see them during the day. And rule number 3, never feed them after midnight. Meaning she doesn't sleep over and you don't have breakfast with her ever.

Robin: Where do you see this relationship going? My God, that sounds so cheesy.
Barney: I know, right?
Robin: Totally. But hum... Where do you see this relationship going?
Barney: I don't know. I mean, it's not like I don't like you. I just haven't had a girlfriend for a long time. I hope that doesn't make you mad.
Robin: Mad? I feel the same way. I suck at relationships. I mean, except with Ted. Man, he really got it right. I know it's a cliché, but... he really ruined me for other men.
Future Ted: [v.o.] Of course, I wasn't in the room for this conversation, but I have to imagine Robin said something like that.

Future Ted: [v.o.] After that, the summer went by way too fast. Until all of a sudden, it was the Friday before my first day as a college professor.
Ted: Whoa, what's this?
Marshall: It's just a little something that we got for you that used to belong to my favorite professor of all time.
Ted: A fedora! [puts the hat on and removes a whip] I'm Indiana Jones! I'm Indiana Jones!!
Barney: That, my friend, is the Dominator 8000, the best bullwhip on the market, according to my whip guy. Yeah, I have a whip guy. [whip cracks]

Ted: I am freaking out. I don't think I can do this.
Barney: Okay, look, mistake number 1 was taking that girl's question. You don't take questions on the first day. It shows weakness. Mistake number 2 was you should've hit that. Dude, your pants were already off, you had a classroom full of people to cheer you on, and you can't knock her up 'cause it's a dream. Class dismissed.
Marshall: Mistake number 3, dude, where was the hat? Cause if you're not going to wear it, I'm taking it back.

Future Ted: [v.o.] I still hadn't decided what kind of professor I wanted to be, authoritative or cool guy. I thought I would decide in the moment. And I did. About 20 times.
Ted: Good morning. What's up, dudes? Silence! This is Architecture 101. I am Professor Mosby. But you can call me Ted. Professor Mosby. T-Dawg. Do not call me T-Dawg.
[The blonde woman raises her hand. Ted imagines Barney appearing as a guru.]
Barney: Never take questions on the first day. It shows weakness. Also, don't look right here [points to the woman's breasts] Okay, good luck. Byesies.
Future Ted: [v.o.] This was it, my crossroads moment. What kind of professor was I gonna be. I had to decide.
Ted: Please save all your questions until the end of the lecture. Thank you! Now...
Future Ted: [v.o.] Professor Mosby had arrived. Of course, if I had taken that girl's question... who, by the way, was not your mom. Your mom was sitting... Wait, let me finish this real quick. Here's what that girl would have said.
Blonde Woman: I'm sorry to bother you, Professor Mosby, but this isn't Architecture 101. This is Economics 305. You're in the wrong classroom.
Future Ted: [v.o.] Yes, I was in the wrong classroom. And thus began the most humiliating seven minutes of my life.
Ted: Here's your think-about-it for the day. Every single person in this room... is already an architect.

Ted: Can anyone here tell me what this class is really all about?
Man: Economics? [all laugh]
Ted: Don't laugh. He's not... He's not entirely wrong. An architect must be economical in his use of space, so well done. Looks like someone's building towards an A. Huh?

Ted: You. Why do you want to be an architect?
Man: I don't want to be an architect.
Ted: Yes, exactly. It's not something you want to be. It's something you need to be. You don't have a choice, right? None of you has a choice. [all raise their hands]
Ted: No questions!

Ted: So if any of you have even the slightest inclination to do anything with your life other than become an architect, you're wasting my time and yours. There's the door... You can go. I'm serious. Get out, now.
[All the students gets up to go]
Ted: Whoa. Wait, wait, wait. Don't all leave! Architecture's fun! Look, I brought a hacky sack!
Professor Calzonetti: [enters] Sorry I'm late, everyone. My name is Professor Calzonetti. This is Economics 305. You may return to your seats.
Ted: Sorry, sir. This is... Architecture 101. Who invited their dad, right?
Professor Calzonetti: Young man, for the last 28 years, Economics 305 has been taught right here in building 14, room 7.
Ted: Uh, yeah, buddy, I'm sure 200 architecture students and their professor all got the room wrong.
Man: T-Dawg, you're in the wrong room, bro.

Future Ted: [v.o.] Kids, on my first day as a college professor, there were two things I didn't know that I wish did. The first thing was that your mother was in that classroom.
[A blonde woman raises her hand.]
Future Ted: The second thing? Well, to explain that we have to go back to the beginning of the summer. When, after a year of wrestling with their feelings for each other, Barney and Robin finally, well...
[montage of Barney and Robin being together]

Lily: Whoo!
Marshall: Lily! All we need is your indoor "whoo."
Lily: Sorry. [quieter] Whoo! It's just they kissed! They're finally a couple. Oh, my God, you guys! This is our first double date. First of millions. What if our kids get married?! Oh, I love this!
Barney: Yeah, Lily, listen.
Robin: Barney's awesome.
Barney: Robin's more than just awe-"some." She's awe-"quite a bit." She's awe-"a whole darn lot."
Lily: Wait, what are you saying?
Robin: We're just not feeling it right now. But we'll totally still be friends.
Barney: Oh, yeah.
Lily: Is it something I did?
Robin: Oh, no, no, no. God, no. Lily, it's not you. It's us.
Barney: Yeah, It's us. You understand, right?
Lily: Sure, of course. As long as you're happy, I'm happy.