Cher thinks she's really ''immature.''

The 72-year-old singer recently reunited with her friend Meryl Streep for the forthcoming musical movie 'Mamma Mia! Here We Go Again' - in which she plays the 69-year-old actress' on-screen mother Ruby Sheridan - and has admitted she was the one pulling all the pranks on set because she's a child at heart.

Speaking on Britain's 'Lorraine' on Thursday (19.07.18), Cher said: ''I came, I did my best, I had a great time. It was like a party. We weren't acting, everyone was talking, all the boys were so crazy and being silly. All the girls were just sitting and talking and gossiping. I was very scared to go because you're butting in to people who have already been together [in the first film]. They're already set in steel.

''I came late, I was the last one, I was nervous. I'm always kind of nervous. I was born to do this. But also, sometimes people who were born to do this are very - not timid, because I'm not timid - but shy people. So this is their other side, this is the side you get when you get to just be balls to the wall.

''She [Meryl] can be so girly but she's sometimes a little bit more serious. I am always going to her with the sky is falling and she always going, 'It's not falling be quiet.' She's much more a grown up than I am. I'm immature.

''My mother's immature and she's 92. My grandmother she was like going to the gym when she was 85. They had a picture of her up on the wall.''

And, although she's in the seventh decade of her life, Cher believes her youthful looks are down to the fact she's never smoked, drunk alcohol or done drugs.

She explained: ''I didn't smoke, I didn't drink, I didn't do drugs. I think that that has something to do with it, I really do. I've taken care of myself. I'm a good eater.''