Unfortunately I'll have to handle this situation tomorrow so I won't have a lot of your input as to how I should handle it before it happens. I just want (and really appreciate) your thoughts.
Someone (Gail) in our department is retiring through a voluntary layoff program. Since it is technically a layoff there are no plans to replace her so her tasks need to be distributed amongst the rest of us.
I am a graphic designer. Gail is not.
During my annual review yesterday Boss told me of a particular simple task that she would like for me to take on. I agreed, it's really quite simple and since there is some graphic design involved (which I've provided for Gail in the past) it's just taking it to the production level. Sigh. No biggie. Go Team.
I was scheduled to have an instructional 30-minute meeting with Gail and Boss today. Gail was busy and rescheduled. I thought the meeting was rescheduled for tomorrow, but Gail and Boss showed up at my cube at a crucial time (deadline!)
I apologized because I misread the date on the meeting notice, looked at Boss and asked "This or That? Your call." Boss said stay on that.
Here's where the blindsided part comes in . . . Gail told me to reschedule at my convenience tomorrow but plan for more than an hour because not only does this involve simple task but it includes major big task that I will be taking over and is quite difficult to explain.
I looked at Boss as she turned around and headed out the door.
Wait! What?

I'm furious because Gail was the one that told me that I needed training on major big task. I'm all over angry because this task does not fit anywhere in my realm of graphic design.
And boss had the nerve! To walk away!
Like I said, I had a crucial deadline (along with the need to leave on-time today so OT wasn't an option) so I got busy with my task and didn't address the situation. I left it with Gail that I would schedule a meeting tomorrow.
I need to talk to Boss tomorrow and let her know that there is no way, no how I am willing to take on major big task
that really has nothing to do with my job description.PLUS! (I know, anti-meeting me

) doesn't have time for an hour+ meeting in order to meet the deadlines that I already have.
(Two weeks ago I informed my Boss of personal commitments that I have which will not allow me to work OT for the next couple of days. Boss was fine with this.)
What is the business-polite way to handle this situation? Am I allowed to refuse taking on the extra major big task?