William Shatner's goofing on Sarah Palin's farewell speech was funny the first time.

The second time, when Shatner tried to make fun of her Tweets, he plopped and flopped -- all while the musicians behind Shatner were mugging for the camera in a wholly inappropriate manner.

We can't believe Bill Shatner -- after so many successful years in showbusiness -- doesn't know you can't play the same moment twice.

Now, if George Takei had performed the Palin Tweets instead, sweet history would've been made into money, honey.