Buzzed Bobby
In “The Sting,” a sixth-season “Dallas” episode, an anxious Donna (Susan Howard) is on the phone in her living room.
DONNA: Bobby isn’t there either? Uh-huh. Then you haven’t heard from either one of them? Well, do me a favor, Teresa. If Ray comes up there, would you tell him to call me at home? OK, bye.
She hears rustling outside. The patio door slides open and a tipsy Bobby and Ray (Patrick Duffy, Steve Kanaly) enter.
BOBBY: [Giggly] Hi.
DONNA: Where have you been? [Ray walks toward the kitchen, followed by Bobby.] Well, maybe I need to make some coffee.
BOBBY: Oh, wait a minute now. We’re not drunk.
DONNA: Well, you could have fooled me.
RAY: Now, hold on. [Laughs, tosses Bobby a beer] Here! Just what you need, huh? [Slaps him on the shoulder] We just had a couple of beers in celebration. [Laughs, plops on the sofa]
DONNA: Well, celebration. That’s terrific. I guess you know you’ve had me half worried to death!
RAY: Worried? Why?
DONNA: Why? [Motions toward Bobby] Ever since he called, you two have been running around like crazy. I mean, you don’t tell me why or what for! Do you know what time it is?
RAY: [Rises, approaches her] Oh, honey. I’m sorry. I didn’t mean to scare you.
DONNA: You know you could have called your wife, Ray Krebbs. Would you like to tell me what it is you’re celebrating?
RAY: Think we ought to tell her?
BOBBY: [Slurry] We rode out in the spirit of John Wayne, Donna.
RAY: Yeah, we headed J.R. off at the pass. [Guffaws]
DONNA: What are you talking about?
BOBBY: OK, in plain English?
DONNA: Please.
BOBBY: [Deadpan] J.R. … [Cracks up, along with Ray] will never sell guns to the Indians again!
Dallas Decoder 
Do you get the feeling this scene was played the same way any practical joke on the set was played?
Yes, Dan, I do! Good point.