Silver the giraffe: It's a giraffe named Silver who's walking and there's a helicopter passing by. And Quick ... Silver!
This French joke is based on a play on words. Here, the giraffe named Silver is walking around and there's a helicopter passing by. 'Quick Silver' is pronounced similarly to 'Quicksilver', which is a common term for the element mercury. It's unexpected and absurdity is what makes it funny.