From Ensign3, The 4th Doctor and the real Sherlock Holmes are held in a maximum security cell having a discussion, at the end of which the Doctor simply gets up and says the following:
The Doctor: Well then, shall we be on our way?
Holmes: You speak as if you have a plan of escape. I've been at it for days but to no avail.
The Doctor: Not so much a plan of escape as a very convenient oversight in our favor. You see, there's a funny thing about those who are very powerful but also very stupid.
He removes a bag of jelly babies (with the sonic screwdriver inside) from his pocket.
The Doctor: They never learn and they don't check pockets. Jelly baby?