Kolkata is the most conservative city in India. So forget about girls..!!
Well...you can visit Victoria Memorial.
Have some live p0*n at Eliot Park..!!
You can also consider watching classic movies at Nadan.
Or if you are an artist visit the Art Gallery beside Nandan. Birla Planetarium is also good. All these are on Rabindra Sadan.
Otherwise have some good time at Bars, Discos at Park Street. Someplace Else at Park Street is a must for music lovers specially Jazz, Blues, Rock. If you are an Historic person then there is Museum there also.
Or have some shopping at Esplanade...!!
Or you can consider visiting red-light area Sonargarchi at Sobhabazar Sutanuti
Or have some greenery look at Maidan..!!
Other places will be tough to cover within the time span you mentioned.
Like you can visit Nicco Park, Science City, Aquatica etc but that would need a whole day. But I think you can cover Millenium Park and have a ride on Streamers that would cross by Howrah Bridge.