To have a thought or idea, and forget it right away. As if you came up with the idea while staring at one of the Silence, and then looked away.
Coming from Doctor Who, where the order known as the Silence are "memory-proof", so you can only remember them while you look at them, and you forget them when you look away. The Silence uses post-hypnotic suggestion to make people do their bidding without people realizing what they're doing or why.
Doctor: "Amy, Rory: I have a great idea!"
Amy: "What is it?"
Doctor: "Uhh… I forget…."
Rory: "Hah. You just Silented!"
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)