Non-dev activity that made me a better dev?

That's an easy one.

Playing the piano. Or better: learning to play the piano.

(With the help of my teacher) I developed many skills that help me learn faster and I learned how to properly use and organize my time.

So, here is the worst experience, not one.. but recent two of many of the encounters I had with my OOP teacher... (I am in Second Year of Engineering). Lets Call him T.
To give a background of T... He knows nothing but acts like he is the master... you'll get to know this...

Incident #0:
*me developing a website for a client and T just bumps in*
T: Hey, what are you upto.
M:Nothing sir, just some Web-dev stuff.
T: What languages do you use?
M: I am currently using embedded ruby.
T: No no, I meant, what languages do you use for web-dev?
*inner* M: Ok, try to act stupid... He is not worth of all the knowledge.
M: Sorry sir, I just use simple HTML-CSS.
T: Ohh, I use Wordpress... It's a great language to build websites.
*inner* M: He has no idea what WP really is, he is a fuckshit.
T: It's so simple and easy, that you code for Desktop view, press Ctrl-M and then it automatically makes it for mobile view.
*inner* M: Bursts out into laughter
M: OK sir, will look over it.

Incident #1:
*He is teaching, suddenly topic comes of Oracle Certification for Java*
T: I know many of you have idea about java, but do you have what it takes to be an OCJP..
*inner* M: LOL...
T: It is a really hard thing, and I can bet... I can bet *he did repeat that twice* that no one from you can even qualify OCJP.
*inner* M: It's time... It's time
M: Excuse me sir, first of all it's OCA... OCJP does not exist anymore... And secondly, I am an OCA...
*inner* M: Yeah... Fuck you bitch!
*assucimg inner* T:Fuck, asshole..$#@#%@!@$@%#

And whole class was like -> o.O

Thinking about teaching a friend programming, I'm tempted by Kotlin as he's interested in mobile dev. Reasonable? Also any programming teacher have tips? I've always programmed so not sure how to look at it from a muggle's - I mean non dev view point.