I think Bobby Heenan coined the term once, and Michaels used it ever since.
At least, that's what I remember hearing off of one of Michaels' interviews on Confidential...
Living in the UK i can't confirm this
SHAWN MICHAELS
"Regrets? I only have one - that I wasn't born sooner so that I could have spent more time with myself!"
That sums up early 90's Michaels PERFECTLY.