pull (one's) leg
To tease or joke with someone, often by trying to convince them of something untrue. Quit pulling my leg, I know there isn't a Hollywood director calling me right now. I love pulling my sister's leg—it's almost too easy to annoy her.
pull somebody’s ˈleg
(informal) tell somebody something which is not true, as a joke: ‘You came first! You’ve won the prize!’ ‘Really? Or are you just pulling my leg?’ ▶ ˈleg-pulling noun: The news of his engagement was greeted with much leg-pulling by his friends.