IT’S a wonder Tracy Mor gan never hauled off and slugged Jimmy Fallon on the set of “Saturday Night Live.” The “30 Rock” star tells the Octo ber issue of Penthouse that his castmates were bothered during skits by Fallon’s “laughing and all that dumb [bleep] he used to do – he wouldn’t mess with me because I didn’t [bleep]ing play that s – – t. That’s taking all the attention off of everybody else and putting it on you, like, ‘Oh, look at me, I’m the cute one.’ I told him not to do that s – – t in my sketches, so he never did.”