So I hear my wife answer the door the other day. It was someone dropping off some girl scout info for my daughter. I hear the woman say, "Sorry, I have to run, I've got the gerbil in the car. We just brought him back from the Vet."
I bet in Vet school there's at least an hour discussion of do's and don'ts concerning how to handle the nonsense of someone bringing in a gerbil.
Don't - in a demeaning way say, "Does your husband know that you're wasting money on this bullshit?"
Do - after "fixing" the gerbil say, "Now when was the last time your fish have been in for a physical?"
Don't toss the gerbil into the trash and hand them directions to Pet Smart.
Do make them feel less stupid by saying, "Oh you brought a GERBIL here. I thought the nurse said you brought a FROG here. How ridiculous would that be? A frog? Not you though - you brought a gerbil. There is nothing - I repeat nothing wrong or dumb with what YOU did. Now where is the little guy? (shaking head) A frog...sorry...can't get over that one.
Don't take the gerbil into another room, spray paint a new gerbil haphazardly to match the sick gerbil, then hand the new gerbil to the owners and arrogantly say, "NEXT!"