In Kal Ho Naa Ho, Aman Mathur (Shah Rukh Khan) advises Rohit (Saif Ali Khan) to woo a girl in '6 din' (6 days) - 'ladki in' is a colloquial misprint for 'ladki ko'. This forms a key plot point where Rohit attempts to win Naina's favor within six days. The other options (saat, ek, do) are incorrect.