Battery acid ...

An afternoon in the park, showing my son my very lack lustre frisbee skills. He at least got a lot of exercise as he ran every which way to catch my erratic throws.

Also spent some time indulging in that childhood pursuit of laying in the grass watching the clouds go by. Unfortunately someone had left their empty can to ruin the look, but it was bright and shiny enough to attract my attention for a blip.

Horrid stuff that tastes like battery acid and I've only ever found it useful when studying for uni exams.