It's supposed to be a tree! a tree!
Parisians everywhere (who are members of the far-right group "French Spring") are scandalized by an art installation that is "supposed" to be a tree but appears to everyone (including you, me and even my grandma who has no idea what a butt plug is) as a toy that is meant to pleasure the inside of one's anus by blocking it with an object of considerable length and girth.
The artist, Paul McCarthy, says that his sculpture isn't a butt plug, but according to The Daily Mail, he's also known for his provocative art, like fun animatronic sculptures of George W. Bush fucking pigs. Perhaps the conceit of the project here (and I am not an art scholar, so bear with me) is that he conceptualized the giant butt plug (and the accompanying giant butt plugs you can see, including sculptures of santa holding butt plugs because...) as a provocative object meant to get a reaction and turn it around on the viewer.
"It's a tree," McCarthy might say to a disgruntled Parisian conservative who is angry that this is where the city's taxes are going. "If you see a butt plug, well then that's your own issue, you know? That's just like your opinion, man. And for someone who's so against gay marriage, why are you so worried about ass play anyway?"
For the record: It's totally a bunch of butt plugs.