The pair have worked together on almost a dozen films, with their most famous appearance as the young couple in the 1995 blockbuster "Dilwale Dulhania Le Jayenge."
The movie, which is commonly referred to by its acronym DDLJ, set a record as the world's longest-running movie, clocking up more than 20 years of continuous screening in Mumbai. Shah Rukh Khan says he likes to tell his 18-year-old son that one of his films has been playing longer than he's been alive.
Now SRK and Kajol are reuniting for the first time in five years in a new Bollywood epic, "Dilwale
" - reassuringly typical of the genre by featuring comedy, action, drama and music by the bucket load.
But how well do they really know each other? We decided to put their on-screen knowledge to the test by challenging the actors to reveal each other's on-screen secrets -- with extraordinary results....
CNN: What do you consider to be each other's most irritating habits on set?
Kajol: "I know what he finds irritating about me (laughs). He finds it very irritating that I'm talking all the time. I am talking ALL the time!"
SRK: "No, she's the very quiet, strong, resilient type." (laughter) "This is right, I would have said the same thing, that she loses focus and screams a lot and talks a lot in the middle of the scene and I'm OK because we've know each other for 25 years, we work together like this. But other actors are there thinking 'Is this how it's going to be for the next hundred days? Because she's screaming and we don't know if she's making fun of us.' They can't tell. They get a little intimidated with it."
CNN: Who messes up most?
(Kajol puts her hand up and SRK points to her.)
Kajol: "I do." (laughter)
SRK: "The cause of the mess-up is she's a very natural actor -- she knows her lines, she knows her space. But she's not bound by "OK I'll do this, I'll turn this time, I'll do this and many times while acting she loses grip of everything. She's like 'This time I'm just gonna do it' -- she's very free-flowing. (He grips her arm). So I have to keep holding her sometimes in the scenes. Nobody knows this but in the over-the-shoulder-shots she's sometimes left the shot and gone away and I'm pushing her from one side or prodding, while we're shooting an emotional scene and both of us are crying and I'm pushing her because she just moves away and I don't want her shot to be lost. Because she's doing it well but she's just moving away somewhere else and doing it. So the technical part of it..."
Kajol: "I screw up..."
SRK: "...she doesn't believe in it..."
Kajol: "It's not that I don't believe in it it's just that I get carried away sometimes."
CNN: What is the one thing that SRK cannot do without on-set?
Kajol: His cigarettes!
(SRK Looks aghast!)
Kajol: "Oh My God I shouldn't have said that!"
SRK: "She means cigarette sweets!" (laughter)
SRL:" Secrets, she said "secrets."
Kajol: "Secrets is what I said."
SRK: "Not cigarettes". (laughter)
SRK: "She can't do without her food and it has to be sitting right there next to her more than the make-up person or the dress person and (he imitates her snacking) so she's always eating. Food is very important to her."
Kajol:" It's important to everyone else as well that I don't turn into a raving lunatic if I don't get my foods."
SRK: "Yeah, that too! We need to make sure she doesn't attack people and head-butt them and so we need to make sure she has food always available. (laughter) As a matter of fact in the props we keep food so she can always have it." (he gestures her stuffing her face)."
CNN: What are each other's diva demands?
Kajol: "Diva demands? Yes! He's a BIG diva! Shall I say it?"
SRK: "Yes, if you're lying about me throughout the show why not lie some more? Cigarettes!" (laughter)
Kajol: "No, I think the biggest diva demand is that wherever we are going, he has to be the last one on the aircraft, that is his big diva demand. 'Whatever happens I have to be the last one on the aircraft'. Even if everybody's biting their nails and the pilot's about to take off 'I will be the last person on the aircraft.'"
SRK: "It's not a demand..."
Kajol: "It's a DIVA demand!" (pointing her finger accusingly).
Kajol: "The only thing missing is the black lipstick.
SRK: "I swear guys I'm going to buy my own plane!"
CNN: What is the best thing about working together?
SRK: "There's no fake courtesy. We don't have to start off as introductory actors. We haven't worked (together) for five years. When we met on the set six months ago. When we came to do the first scene, which was me meeting her for the first time in the film in Bulgaria, it seemed just as though it was five years ago. There's a huge openness in being able to respect each other so much that you can be critical and appreciative at the same time, she can turn round and say "I don't like that, why do you look like that in that scene...?"
Kajol: "There's no ego.."
SRK: "And I know that if she doesn't like it, along with the director, she's my first line of knowing whether I've got it right. That doesn't happen with all actors. I know that if she doesn't like it I'm not gonna question it I'll just do it again. Similarly I can tell her "that was very nice but can you do this? Oh yeah OK I got it" and it's very instinctive and natural now and both of us -- she would like me to be the best thing in the frame and I would like her to be the same."
Kajol: "We take care of each other, in every which way."