Random Doobings

It was a dejected and rather red-faced Captain Doobie that walked through the front door. He was followed shortly after by a resigned-looking Goodtime Slim.
"Shall I put the kettle on?" asked Captain Doobie with false brightness.
Goodtime Slim's glare was all the answer he received.
"I don't see what you're upset about," said Captain Doobie as he slommocked his way over to the couch, "It's not like you did anything."
"No," replied Goodtime Slim in what could only be described as a biting fashion, "I didn't need to. You did the lot, didn't you?"
"It's not my fault!" Captain Doobie wailed.
"Isn't it? Whose bloody fault is it then?"
There was a pause.
"Alright, it is my fault," conceded Captain Doobie, "but I do wish you wouldn't take on so."
Goodtime Slim settled back in his chair and folded his hands above his small paunch. "What have we learned today?" he asked, "and by 'we' I mean specifically 'you'."
"That it's important to dress for every occasion."
"Indeed. Any why, in this specific instance was that a requirement you should have followed?"
"Because I had paint splattered on my trousers."
"What colour paint?"
"Red."
Goodtime Slim nodded. "So, with red paint splashed all down your pants, where should you have not gone?"
Captain Doobie nudged the floor with his toe. "The blood bank."
"Exactly. If I were you, i'd send them a bunch of flowers or something."