11-01-17
In Dog Day Afternoon, before letting FBI agent Sheldon enter the bank to see that the hostages are OK, Sonny frisks Sheldon, and a crowd of LGBT people responds with Ooo's. Sonny than makes an open fist hand gesture towards them, (see the picture below) and they increase their cheers.

What's the meaning of that open fist hand gesture? (I guess it has some sexual or LGBT-related meaning)