Sad, but true. Great Grand Masti has just not managed to find an audience for itself. If the opening occupancy was quite poor with hardly any audience, especially in multiplexes, even at single screens (its target audience), there weren't any major footfalls that would have made those who had invested in it breathe easy. The collections didn't improve much during rest of the day either since a) there was hardly any audience to spread word of mouth and b) whatever word of mouth came out wasn't enticing enough.
Result? The film brought in only Rs. 3 crore* at the Box Office, which is very low for all involved. In fact if one compares the film with other adult comedies from past and present, this is how Great Grand Masti stands, as far as the opening day is concerned:
Grand Masti - Rs. 12.5 crore
Kya Kool Hain Hum 3 - Rs. 8.15 crore
Kya Super Kool Hain Hum - Rs. 7.12 crore
Mastizaade - Rs. 5.59 crore
Great Grand Masti - Rs. 3 crore*
An interesting trend to see is that Kya Kool Hain Hum 3 that reached the peak for its franchise ended up disappointing a large segment of audience with its poor content and alienated them from the adult comedy genre. The after effects were felt first for Mastizaade which saw a much reduced foot print going for it. Now with Great Grand Masti, it has reached its low as the audience for this genre has just disappeared.
Yes, the makers did come up with a good idea to pitch Great Grand Masti as a unique mix of adult comedy and horror. However, the audiences had clearly made up their mind. Did piracy impact? Yes. However, even that doesn't explain the 75% fall in collections that the franchise suffered from when compared to its last installment, Grand Masti, which went on to collect 100 crore in the long run.
*Estimates. Final numbers awaited
Note: All collections as per production and distribution sources
