<p>Looks like a return of favour. Back in December 2013, Salman Khan had lifted the lid off many a well-kept secret in a no-holds-barred first episode of 'Koffee With Karan 4'. Now, as the star gears up for 'Bigg Boss' Season 10, Karan Johar is likely to feature in the show's opening episode to promote his Diwali release, 'Ae Dil Hai Mushkil'</p>