Justin Bieber just can't seem to stop monkeying around. 
The pop star's capuchin monkey was confiscated at a German airport last Thursday after the Biebs failed to provide proper paperwork.
"Justin Bieber brought his monkey to Germany but had no official paperwork with him," Thomas Meister, spokesman for the customs office at the Franz Josef Strauss Airport in Munich, told People. "We were forced to confiscate the animal."
Is Bieber heading into Michael Jackson territory, or what? 
Jackson, of course, adopted his infamous chimpanzee Bubbles in the early '80s, reportedly letting the ape sleep in a crib and use his toilet.
George Clooney was just as smitten with his pet pig, Max. 
"Pigs are really smart. And he was funny, and he made me laugh," Clooney told Charlie Rose of his pot-bellied oinker, who died in 2006.
And don't get Mike Tyson started about his love for pigeons. 
"The first thing I ever loved in my life was a pigeon. I don't know why . . . I feel ridiculous trying to explain it," the tough guy ex-boxer said in 2011 while promoting his pigeon-racing reality show "Taking on Tyson."
"Queen of mean" billionaire Leona Helmsley — best known for her alleged quip that "only the little people pay taxes" — left her Maltese, Trouble, a $12-million trust fund (the sum was later reduced to $2 million).
Entertainer Roy Horn — one half of the Siegfried & Roy duo — was bitten on the neck in 2003 by their white tiger, Montecore. He was critically injured but learned to walk again.
And who can forget Paris Hilton's Chihuahua, Tinkerbell, who went just about everywhere with the heiress and even kicked off an (annoying) dog-as-accessory trend?
From Bieber's monkey to Clooney's little piggy, click through our slideshow and let us know: Which celeb had the quirkiest pet?