1. I was getting around to it. - they completely forgot whatever the hell it was and still don't understand what you are talking about.
"So, Dean. When were you planning to tell me about your little stint with the angels?" Sam said, grinding his teeth.
"Hmm?" Dean replied, continuing to wolf down his bacon and eggs with a perfectly innocent expression on his face.
2. I'll call you. - hell will freeze over before you will hear from them again.
"Bye Sam, have a good time screwing the devil. I'll call you if things get slow in reality."
3. I've been busy. - they haven't.
"So what took you so long?!" Sam practically shouted, very tempted to take a swing at his brother.
"What?" Dean asked. "I was busy!"
4. What are you wearing? - Their way of asking if you're decently dressed... for sex.
"Where are you, Sam?" Dean asked casually.
"I'm back at the room, Ruby's here waiting for you."
"What are you wearing?"
"Me?"
"No, put her on the phone."
"What?"
"Fine. What are you wearing?"
"Clothes...?"
"Oh, thank god."
"What are you-"
"See you later, Sammy."
5. That's interesting. - They haven't been listening to word you've been saying and at this point only want sex.
"Dean, are you listening to me?"
Dean obviously wasn't, he'd had his eyes glued to some cowgirl's ass for the past 30 minutes.
"I said that the only way to kill it is to stake it under the full moon and then salt and burn."
"That's interesting." Dean replied, eyes riveted on a mini skirt.