Most outsider characters at the office will be dogs, because I work at a very dog-friendly office, and it keeps me from spending hours just trying to decide what species a one-shot character will be. I might give attributes of the real-life office dogs to characters based on humans that visit the office as well.

↓ Transcript
The ferret employees are gathered at a meeting when a yellow labrador walks into a sign that says, "Business coach time!". He is the business coach. "Well, it's like walking into IHOB here! You know, because of all the hobs..."
A ferret interrupts, "Another pun about a word that only refers to the un-neutered, male ferrets in here?"
The business coach goes on with business. "We're going to start out with a unique version of 'Pop Goes the Weasel' as a team-building activity...", which elicits a groan from all of the ferrets. The dog continues, "...Is there any mud near the building? Now, I'm sure you're all wondering, 'Is he serious?'"
A ferret mumbles out, "There wasn't even a question".
A second ferret interrupts ecstatically, "Let's do it!". He will be woefully disappointed because the labrador was, indeed, not serious.