The Ruletta Trophy
You played the Wheel of Songs mode.
This trophy takes a few seconds to do. Even though it is a party mode, you’ll only need the one microphone plugged in, because the trophy unlocks before the round even starts, even if the random mode requires 2 microphones.
Go to Main Menu > Party > Wheel of Songs. Pressing will randomly select a song and mode, and pressing again will start the selection. While whichever scenario is loading up, the trophy will unlock. Feel free to quit immediately after this.