Well, 20 is better than 39....

[Brad from Georgia]

One of Jack's routines (guess which) has wound up in the GQ list of the 100 greatest jokes of all time at number 20. http://www.bluedonut.com/100jokes.htm

[LLeff]

One of Jack's routines (guess which) has wound up in the GQ list of the 100 greatest jokes of all time at number 20.

And they didn't even get the punch line right! Gahhhh...

[River Phoenix]

One of Jack's routines (guess which) has wound up in the GQ list of the 100 greatest jokes of all time at number 20.

And they didn't even get the punch line right! Gahhhh...

It might have been "I'm thinking", sans "it over", in one of the versions of the gag (not the original). I seem to recall hearing a recording of it in which Jack just says "I'm thinking". IIRC, when I heard it I flinched because it just isn't as funny.

[Alan]

Just a slight change makes all the difference between "ok" and lasting brilliance; A good reminder of how very difficult comedy is, and the awesome talent of the JB crew (and many others).

The old story applies (or at least one variant);

a great comedian is on their death bed, and a loved one says, "it is difficult to be losing you"..the dying comedian replies "dying is easy, comedy is hard."