[flashback to earlier that night:]
Barney: Hi, Shannon.
Shannon: What are you doing here?
Barney: Just listen. When you left me for that guy Greg, it changed me. Now, I'm this. I-I know this is crazy. It's just, you were once such a big part of my life. And it just seemed insane that you didn't know who I am now. So here I am. And then she told me about her life.
[back:]
Barney: She and Greg dated for a while and then split up. But here's the real kicker: Shannon's a mom. She has a little kid named Max. That's crazy. That could have been my kid. But instead, what do I have? My whole life's some money in the bank, some suits in my closet and a string of one-night stands.
Lily: Hey. Come on. I mean, just because her life went one way and yours went another, it doesn't make your life any worse.
Barney: My life rocks! Money, suits and sex. These are tears of joy! I could be cooped up in some tiny apartment changing some brat's poopy diapers. But instead, I'm out in the world being awesome 24-7, 365! You let me dodge a bullet, Big Guy.