Jennifer Lopez made Leah Remini ''cry from laughter'' when she slapped her best friend on the set of 'Second Act'.

The 49-year-old singer and actress stars with her close friend Leah in the new movie, and managed to make her burst into tears through intense laughter after an improvised scene ended in a jovial ''slap''.

In one scene, Leah's character Joan gives her best friend Maya (Jennifer) a pep talk before applying to a high-ranking corporate job, and Leah decided to improvise a little by calling on the phrase ''Who's the champ?'', which she often tells Jennifer before her concerts.

Leah, 48, said: ''This time I decided I'd slap her. She slapped me back so hard it made me cry from laughter.''

The pair had a ''natural chemistry'' on set as they've been close friends for years, and Leah claims the bond on-screen looked so ''real'' because they ended up ''improvising'' so much that the final product was the two actresses showcasing their own relationship.

She added to Entertainment Weekly magazine: ''A lot of it was improvised. Her reaction is always funny because that's her reaction to me; she rolls her eyes a lot if I grab her boob or annoy her ... Annoying her makes me laugh, so I'd do different things in different takes, so you're seeing her real reactions.

''When you have a real relationship with somebody, you can't write that stuff. I'm comfortable with her; I'm used to cuddling up to her, to grabbing her arm when we walk, and she's used to grabbing my arm when we walk. There are little things [in here] where you go, 'This is our relationship.'''

Earlier this month, the pair heaped braise on each other during a separate interview, where Leah said the 'On The Floor' hitmaker was ''loving'' and ''authentic''.

She said: ''She's loving, warm, fiercely loyal, courageous, brave, true, authentic ... there's a lot of things.''

And Jennifer added: ''We understand each other's lives. I'm so close to my sisters and so is Leah, but we have similar lives. We have similar careers, so we understand nuances that other people don't understand. That also bonded us, I think.''