"In Your Copious Free Time"

I e-mailed Somerville's new mathematics freshers for the first time today, so it was time to introduce them to important phrases --- such as "in your copious free time". (I heard this in the past from people like Mark Newman and Barry Simon, and I am sure that its use in academia far predates the latter.)

Didn't you know? Free time at Oxford is always "copious".

Update (9/10/13): I was listening to Tom Lehrer yesterday, and he uses this exact phrase in the same snarky way. I wouldn't be surprised at all if that is a common origin for how many of us started using it. (It occurs in the introduction to the song "It Makes a Fellow Proud to Be a Soldier.")