Slang for when someone loses there focus or ends up failing to do what the had set out to do.
When I failed my chemistrytest, 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.
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.