I know a lot of RF Cafe forum readers are not hams so you have no idea what "straight key night" is. You don't even know what a "straight key" is.
When you see a person sending morse code in the movies or on tv, they virtually always using a "straight key". This is nothing more than a normally-open momentary switch that has been designed to be comfortable and adjustable for the telegrapher. However, speed is limited to around 20 wpm for most operators. You just cannot go any faster than that for more than a couple of minutes.
So in the second half of the 1800's there were many inventions to speed this up. "Semi-automatic keys" and "automatic keys" were mechanical wonders that would use resonant mechanical structures to produces the dits and/or dahs. This made speeds up to 50 words per minute quite practical. Then in the 1950's we had the development of 'electronic keyers'. These used tubes (yes they did) and later solid state circuits to produce faster and more accurate timing for dits and dahs. And of course in the 80's with the cost of personal computers dropping, there was the development of software that would transmit "perfect" code from what was typed on the keyboard. So speeds increased again, often up to 70 wpm. Though technology is great, these devices also meant that we all started to sound the same.... there was no 'personality' to the code.
Anyway, on the evening of the New Year we have an informal operating event in which many thousands of hams get out the old "straight key" and have conversations on the air with international morse code. The speeds are slower, and more relaxed. Each operator has slightly different timing and style which makes us identifiable on the air before you even hear the callsign. (Much like an speaking accent gives an immediate clue as to your geographical location during your childhood.)
If you 'know a little bit of code' or have not listened to it in a few decades, then December 31 might be the time to turn on the radio. Many operators will be going as slow as 5 wpm.
Another emerging 'tradition' is to "warm up the old boatanchor". Get the vintage tube equipment fired up (warm up the house), re-form the capacitors and get on the air with a signal that is not perfectly stable. This adds a bit more personality to the signals we will be hearing.
A good place to start listening would be 7.025 through 7.100 MHz around sundown on the 31st. Later in the evening you might drop down to 3.525 ~ 3.600 MHz and see whats going on. Click here for a short video
of a "how to use a bug" (semi-automatic mechanical key) and a video of a 'straight key" .