You Can Play Additional Tunes Too
To celebrate Play Happy Birthday on the Sackbut Day, you're going to need a sackbut.
Yes, a sackbut is a real thing. (This is also a thing.) Yes, it sounds kinda funny or gross, depending on you point of view.
A sackbut is the precursor to the modern trombone. I don't think they're especially difficult to find. It's just that you'll have to acquire one, if only temporarily.
A quick search of my local Craigslist didn't produce any results today, but your mileage may vary.
Perhaps you can rent one (by the hour?) from your local brick-and-mortar (or concrete-and-steel) music store.
Once you have one in hands, you'll need to learn (quickly) how to buzz your lips to make (hopefully) musical tones on the instrument.
After that, it's just a matter of figuring out what position to place the sackbut's slide in to get the proper notes for Happy Birthday. Should be easy peasy, George and Weezie (as the local Penny Mustard radio ad says).
Da Unyun would love to hear your (YouTube) rendition later today. Please share.