You can find Weinberg’s famous Rule of Three in a variety of formulations. Here’s a couple that showed up when I went looking just now (1, 2):

If you can’t think of at least three things that might be wrong with your understanding of the problem, you don’t understand the problem. 

If I can’t think of at least three different interpretations of what I received, I haven’t thought enough about what it might mean. 

At work I challenge myself to come up with ideas in threes and, to keep that facility oiled, when I’m not testing I challenge myself to turn the crap joke I’ve just thought of into a triad. 
By providing constraints on the problem I find the intellectual joking challenge usefully similar to the intellectual testing challenge. Here’s an example from last week where, after I happened onto the first one, I constrained the structure of the others to be the same and restricted the subject matter to animals:
  • If I had three pet lions I would call them Direct, Contour and What’s My.
  • If I had three pet ducks I would call them Via, Aqua and Paroled On The Basis Of Good Con.
  • If I had three pet mice I would call them Enor, Hippopoto and That Would Be Like Turkeys Voting For Chris.
As an additional motivational aid I’ve taken to punting the gags onto Twitter. You can see some of them here … but remember: I never said they were good.
Image: De La Soul