Hello Boys

Crowley with Sam, Dean and Bobby in 5.21 Two Minutes to Midnight.

A: Hello boys. C: That's my line.. – Abaddon & Crowley, 8.23 Sacrifice

'Hello, Boys' is the signature greeting said by Crowley to Sam and Dean.

5.21 Two Minutes to Midnight

Crowley: ...Hello, boys. Pleasure, et cetera. Go ahead. Tell them. There's no shame in it.
Sam: Bobby? Tell us what?

6.07 Family Matters

Crowley: Well, that was dramatic.
Sam: Crowley?
Crowley: Hello, boys. What an unexpected treat.

7.08 Season Seven, Time for a Wedding

Dean: Yeah, you said it. You're in a world—
Crowley: Hello, boys.
Dean: Oh, crap.

7.22 There Will Be Blood

Sam lights a match and tosses it into the bowl. Flames rise up from the bowl and Crowley appears.
Crowley: Hello, boys.

7.23 Survival of the Fittest

Meg: Well, I'm sorry about that, but I'm outie. He could still sh–
Crowley: Show up at any time. Hello, boys. Sorry I'm late. This is an embarrassment of riches.

8.01 We Need to Talk about Kevin

Sam: Dean!
Sam passes the knife to Dean, who is struggling with the other demon. Dean kills the demon with the knife.
Crowley: Hello, boys.

8.02 What's Up, Tiger Mommy?

Sam: It's okay. It's okay. We just got to come up with a plan "B."
Crowley: And what, pray tell, could possibly have been plan "A"? Bring the Prophet to the most dangerous place on Earth, memorize the tablet, and then vamoose? Hello, boys.

8.19 Taxi Driver

Dean: What the hell?
Crowley: Hello, boys.
Bobby: I'd know you anywhere.
Dean: Let him go, Crowley. He doesn't belong in Hell.

8.22 Clip Show

Crowley: Hello, boy.
Sam: Crowley.

8.23 Sacrifice

Crowley: Hello, boys.
Sam and Dean turn to their right and see Crowley standing about 50 feet away from them.
Crowley: What's that old expression? Success has many fathers. Failure is a Winchester.

9.10 Road Trip

Crowley: Hello, boys.
Dean: Here's the deal – you're gonna tell us how to hack an angel, and I'm gonna give you some of the good stuff.

9.16 Blade Runner

Crowley: Hello, boys.
Dean: [kicking a foot of a dead body on the floor] And what do you call this?
Crowley: Refreshments?

12.01 Keep Calm and Carry On

Crowley: Hello, boys. (said to Jarvis not Sam and Dean)
Jarvis: Lucifer? I, uh, have to go.

12.07 Rock Never Dies

Crowley: Hello, boys. Long time. We team up to save the world, and then bupkis. You don't call, you don't write.
Dean: Yeah, we don't care.

12.23 All Along the Watchtower

Sam: Yeah, but not our kind of weird. Look, whatever this thing is gonna be, it – it's gonna be big and bad–
Crowley: You rang? Hello, boys.
Dean: [punches Crowley and holds the demon knife to his throat] Did you do it? Did you let Lucifer out?!
Crowley: I didn't "let" –
Later in the episode...
Dean: Oh, come on!
Crowley: Hello, boys. Again.
Sam:' Wait a second, how the hell did you –