Munnabhai MBBS was one of the greatest hits of 2003. It is said that initially Shahrukh Khan was supposed to play the eponymous role that Sanjay Dutt eventually did with such elan. But apart from the commercial success that the film enjoyed, it was also a very well written movie with many memorable lines. The line featured here comes when Masood (the hospital sweeper played by Surendra Rajan) is cribbing about how many times he has to clean the same area in the hospital. Munnabhai (Sanjay Dutt) goes and gives him a big hug (or jaadoo kee jhappee) as he calls it and thanks him profusely. When he does that, Masood completely melts and his entire demeanour changes. As Munna continues reinforcing the positive message about his appreciation for what Masood does, Masood stops him short and says
"Bas. Rulaayegaa kyaa"
"बस. रुलायेगा क्या?"
Literally it means - enough, do you want me to break down and cry? But the figurative usage could be everytime, you have a discussion with a relative, a colleague or friend and that person is using a very sentimental tone. He could be praising you, thanking you or even referring to you - but in a sentimental or emotional manner. That is when you would say
"Bas rulaayegaa kyaa"
"बस रुलायेगा क्या"