The word “souvenir” means “to remember” in French, so the best souvenirs are memories. But the best memories are quirky ones.
I once knew a man who had to pour champagne on the cruise ship captain’s head on every single cruise he went on. He did this at the kick-off party for every cruise, but also did it on the night when the crew built the champagne tower — just to see if he could get away with it. This led to some incriminating photos — and captains who smelled like bubbly!