Alright, I'm just going to guess that this is a re-post because I'm sure somebody posts it every year. I'm new to the forums though so I'm not going to look through a years worth of posts..
This might also be intended but I don't think it is judging by the "duration 0 sec." on the item.
I discovered this 4 years ago when I grabbed a Filled Festive Mug on new years eve on all of my toons. I was expecting the item to disappear later that night when its "duration" was finished. Instead it stayed in my bag for the entire year and acted as a very helpful 30 second parachute anytime i needed to jump from a high place or found myself falling by mistake (like stepping onto an elevator that actually took off 3 seconds ago).
The item itself can be used and reused, I haven't found a set number of times it can be used but if you want this free item to keep throughout the year grab it now before the night is over!
Happy New Years and enjoy the slow falling!
Another great place i have found this useful is in Arathi Basin, when you're at the Lumber Mill. You can drink it, get on a passenger mount like a mammoth and have your friends jump on, then jump safely down to BS with 30 seconds of slowfall.
Once again, sorry if it's a repost.