(Cover) - EN Showbiz - Robert De Niro has been playing practical jokes on Bradley Cooper.

The Hollywood stars met while shooting 2011 movie Limitless. They struck up a firm friendship and have remained close.

Both love pulling pranks, with Robert organising a joke on Bradley almost as soon as filming ended.

"After finishing Limitless, De Niro sent a dozen pizzas to Brad's home with the toppings he hates most sardines and anchovies!" laughed a source.

The older star is keen to show Bradley he values the friendship though. He knows how much Bradley's pet dog Charlotte means to him, so bought the animal some treats.

"He sent the pooch two pink leather collars and leashes, dog sweaters and treats," the insider told National Enquirer. "Brad was touched."

Robert and Brad are currently shooting another movie together called The Silver Linings Playbook. They have been virtually inseparable on set.

"Brad and Bobby are Hollywood's latest odd couple," the source giggled. "They eye all the cute actresses and swap war stories about the movies they've made." (C) Cover Media