From Bones episode Back in the Saddle:
Booth: It’s got to be (crappy sex).
Bones: Why?
Booth: Why? I’ll tell you why. Here we are, all of us, basically alone, separate creatures circling each other, all searching for the slightest hint of a real connection. Some look in the wrong places, some just give up hope because in their mind they’re thinking there’s nobody out there for me…but all of us, we keep trying, over and over again. Why? Because every once in a while, every once in a while, two people meet and there’s that spark and, yes bones, he’s handsome and she’s beautiful and maybe that’s all they see at first, but making love, making love that’s when two people become one.
Bones: It is scientifically impossible for two objects to occupy the same space.
Booth: Yea, but what’s important is we try…and when we do it right we get close.
Bones: To what? Breaking the laws of physics
Booth: Yea Bones, a miracle. Those people role-playing, fetishes and their little sex games – it’s crappy sex; well, at least compared to the real thing.
Bones: You’re right.