It's a reference to Dana Scully in the tv show The X Files. It's when someone tries to use every exuse before the truth, to get out of something, or stick up for somebody or something.
If you get caught cheating on your bf/gf and you try to make up every possible excuse you can think of, your bf/gf might reply: "Don't Scully me."
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)