I’m clueless as to what a promotion party is...
I got my Blood Stripes “pinned on” by my fellow Company NCOs, when I made Corporal. Brutal and painful, it was worth it.
When I made Sergeant, I was “wetted down” at the NCO Club.
For what it’s worth, my gift was a 5AM, 3 mile run, with one helluva hangover.
Cheers!
LOL, I love military humor. :)