A Naval prank played on new ship members for them to search for a golden rivet in the ships structure. Commonly ambiguous with a homosexual act as an "initiation" of the person. The latter is the generally accepted civilian meaning, however it is not referred to by anyone in the Navy, nor is the term spoken of.
The Golden Rivet is the name of a gay bar in San Francisco, named after the mythical Golden Rivet in the bow of warships. Young male newbies are taken to see it, and when they bend over to see it, they're pantsed and fucked in their bung-hole.
I went to The Golden Rivet when I was an under-age teenager, and some dudes took me to the back room and showed me The Golden Rivet!