Abhishek "Sirji" Bachchan has now become a tree to promote Idea Cellular's new "Green Planet" campaign and the ad has already topped the Business Today-TAM Peoplemeter System's monthly ranking of India's most watched ads. Indeed, after its immensely popular "Walk when you talk" campaign, Idea has latched on to what has become a big trend globally: Green advertising with companies claiming to be environment-friendly. Aircel has already launched its "Save the Tiger" campaign. And it may not be long before others hop on to the bandwagon.