[Jimmy Stewart voice]"Now, you got to believe me Slick, I punched you in the nose because you said you wanted to give me the finger. How was I supposed to know it was as real finger...A Yeti finger at that!"[/Jimmy Stewart voice]
This is all very explainable if you have seen the trailer for the new Rock of Ages movie and seen what Alec Baldwin looks like in it.
Some of the time he got off the set ‘in character’, and, well there you have it...