So, you all know about the Four jersey competitions in the Tour de France right?
There's also a protocol for which jersey you wear if you're entitled to more than one of them, laid out on page 29 and 30 in Article 10 of the Tour de France rules (document is fun throughout for a certain kind of nerd). The rules are simple: the order of precedence is Yellow, Green (points race), Polka Dots (mountains competition), White (best young rider). If a rider is entitled to two jerseys, he wears the most senior jersey, and the second-place rider in that competition wears the jersey.
On the last day of the 2015, the jersey assignments got weird.
Chris Froome was leading the General Classification, so he wore the Yellow Jersey. Froome also led the Mountains challenge, so that jersey got delegated to the runner-up, who was Nairo Quintana, who...was leading the Young Rider competition, and therefore entitled to wear the white jersey.
The precedence rule says Polka Dots trump White, but given that Quintana was outright entitled to the White Jersey, and would have only worn the Mountains Jersey by delegation. The rules are vague on this point, but a sensible interpretation prevailed: Quintana wore White, and the Mountains Jersey went to the third-place rider in that classification, Romain Bardet.
And now, mostly unrelated, my favorite bit of jersey trivia. In 1969, Eddy Merckx won all the jersey classifications. At the time, instead of a "young rider" jersey, there was a "combination" jersey (also white) for the rider ranked highest in the other classifications. Merckx won that with the best possible score, 3. Merckx would have won the young rider classification as it is awarded today, if it was up for grabs. He also won the Combativity prize, and his team won the Team competition.
The only classified overall prize he didn't win was the Intermediate Sprint classification, the prize for the best sprinter during sprints that nobody cares about.