If anyone is familiar with E39 540i cup holders then you know that they are a complete piece of useless junk.
Left the gym one day with a fresh large cup of vanilla protein shake.
Placed it in the passenger side cup holder. Took a sharp left turn and the whole thing tipped over, spilling half onto the passenger seat and half between the seat and the center console.
What a mess. Had a lovely fragrance of rotting milk and vanilla for a few weeks.
Damn cup holder for reference: