20 Things You Somehow Missed In Independence Day
4. The Thinking Cap
Towards the movie's climax, with all hope looking lost, David stumbles upon an ingenious idea to take out all the alien ships in one fell swoop. After his father tells him to get off the floor before he catches a cold, inspiration strikes him like a bolt of lighting and, for some reason, weirdly positions his hand across his head.
According to Jeff Goldblum, this was an improvised decision designed to symbolize David "putting his thinking cap back on". Quite how that's represented with a flat hand across his forehead and not a jaunty little 'm'lady' gesture in reverse, only he knows.