It’s called taint.
When you kill a sexually developed male pig they often release musk and sweat. So it smells like going into a room where a couple just did it.
I used to raise Blue Butts (variety of pig) and have the butcher come once a year after auction to cut them up. The Musk smell isn’t that bad unless done in an enclosed area.
If you don’t, you know someone buried it somewhere in the yard.