In the Zygon Inversion episode of Doctor Who (2005), The Doctor and Osgood had this conversation:
DOCTOR: Oh, your specs are broken. I'll fix them. You can wear mine, they're sonic.
OSGOOD: Sonic specs?
OSGOOD: Isn't that a bit pointless? Like a visual hearing aid?
DOCTOR: What's wrong with pointless? I once invented an invisible watch. Spot the design flaw.
OSGOOD: You're talking nonsense to distract me from being really scared. It's one of your known character traits.
(She puts the sonic sunglasses on.)
DOCTOR: Don't look at my browser history.
(The sunglasses beep.)
DOCTOR: Yeah, I said don't.
Does The Doctor look at... exotic materials on his new wearable tech? Or, is there something else which the Doctor wants to keep private and which can make others jump? Is there anything from the history of Doctor Who to suggest what this is?