Time for some self-indulgence. Ravi is a very common Indian name. And this line does bring the extent of commonness of the name home. This is from one of Javed Akhtar's initial films after his breakup with Salim Khan. You do get some flavour of Salim Javed, but you also feel that the entire 70s was when that couple was on its 'उरूज' or zenith.
The movie being referred to here is the 1984 movie Duniya. Ravi Kumar (Rishi Kapoor was actually called that in this film he he he) goes into a swanky restaurant where Mohan Kumar (Dilip Kumar) has a luncheon date with his friend's daughter Roma (Amrita Singh). He has sights on Roma's purse which he knows contains Rs 10000 in cash. While Roma is waiting in the restaurant for Mohan, Ravi goes in and starts working his charm on her. When Mohan comes in, Roma introduces him to Ravi. Mohan meets him warmly and remarks that he too once knew a Ravi (a reference to the fact that his son was also called Ravi). Our hero Ravi remarks
"जी हां सर ये बात मैने भी नोट की है. कि दुनिया में रवि नाम के इंसान कुछ ज़्यादा ही हैं. अब तो हाल ये है कि अगर आप बाज़ार में पत्थर उछाल दीजिये, तो ज़्यादातर चांस ये है, कि किसी रवि के सर पर ही गिरेगा पत्थर"
"Jee haan sir yeh baat maine bhee note kee hai. Ki duniyaa mein ravi naam ke insaan kuchh zyaadaa hee hain. Ab to haal yeh hai ki agar aap bazaar mein patthar uchhaal deejiye, to zyaadatar chance yeh hai ki kisee ravi ke sir pe hee giregaa patthar"
So if you happen to be a Ravi and face a comment like 'oh I knew so and so; he was also called Ravi", use this. Alternatively you could use this to rib any of your friends or colleagues called Ravi. And if you don't know anyone called Ravi, you have a very sad life.