It's really hard for me to remember выключить because my knowledge of Slavic languages (and understanding of Russian via cognates) comes mostly from southern slavic languages which I have studied, like Serbian, and uključiti in Serbian means "to turn on".

Haha, you've run into some of the most confusing false friends between any languages there. The Russian cognate of Serbian (and Bosnian/Croatian) uključiti is включить, which if I'm not mistaken means the same thing -- not выключить, which means the exact opposite.

To make things even more confusing, the BCS verbal prefix u- normally denotes arrival/entering, whereas in Russian it generally denotes leaving. So you get false friends like ući "to enter" vs. уйти "to go away," or uletjeti "to fly in" vs. улететь "to fly away." Generally, if there exists a Russian cognate of a BCS verb with the u- prefix, it will have the prefix в- or во-, not у- or вы-. The former are real etymological cognates, while the latter are not despite the similarity, and often in fact convey the opposite meaning.

Such false friends are even more fun when you see Serbian spelled in Cyrillic, making the false similarities even more prominent. (The first prize, I think, goes to this one, though my great favorite is also право, which is "straight" in Serbian but "right" in Russian when you give directions.)