It's about the public poll for the Prix Orange/Prix Citron, it's a tradition in Roland-Garros, here's the website:
Fed got the "Prix Orange" (most fair-play, etc.) and Paulo got the "Prix Citron" which used to be for the most unfriendly player (it was a vote of the journalists at the time, they gave it to players like Rios, Kafelnikov, Hewitt, Nalbandian...) and now it means a player with character, with a strong personality.
But which ever definition you take, I don't get why Paulo got it. He shouldn't have been in the list to begin with. I don't remember who the other contenders were (except Djoko because I voted for him), but Paulo was about the least "Prix Citron" of the list.
They asked some players and coaches last time - Santoro, Serra, Barbarin, Haehnel, Wino, etc. - and they all said Fed for the Prix Orange and Nadal, Djoko, Hewitt, Jankovic... for the Prix Citron.