OK. I'll have pity on you and answer the question. It's playing the piano.
That is totally ridiculous, but I am happy you said something Mr. Hoss was at 80% brain energy on this and I was about to get a migraine

When scientists look at brains using FMRIs and PET scans while subjects are doing normal things, the parts of the noggin associated with those things light up as expected.
Playing an instrument involves doing lots of things at once.
It's like a full-body workout for the brain.
Different areas of the brain get into the act.
When you play music, you use fine motor skills controlled by the creative and analytic hemispheres of your brain. There's language involved, and math, too. Plus, feeling, memory, and a lot of everything else your brain can do.
In fact, playing music strengthens the *corpus callosum*, the link between the two halves. Scientists are seeing all kinds of new connections being made as people play music.
This makes musicians great problem-solvers in school and social situations.
Musicians develop higher executive functions.
Musicians get mad skills at interlinked tasks like planning, strategizing, and paying attention to detail because they benefit from learning to quickly handle both cognitive and emotional elements at the same time.
Musicians' memories are also unique.
When musicians process memories, they tend to use an unusual tagging system that lets them file memories in multiple categories.