Slang for when someone loses there focus or ends up failing to do what the had set out to do.
When I failed my chemistry test, I had lost the plot.
I was telling my friend a funny story, but then I lost the plot and started talking about my grandmother’s brownie recipe.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.