Besides blowing on the cartridge...
If a game has emote, I must spam them at the start of a game during a countdown.
I am a bunny hopper, I refuse to walk if a game lets me b-hop. Especially in shooters.
I instinctively crouch jump, even if the game doesn't support crouch jumping.
On games where the map can be discovered, I have to explore every square inch of it. Diablo kills me for this.
Regarding actual traditions: I have to play these songs at least once or twice during Christmas: