The X-Files, Season 4

Mulder:
Hey Scully, if you could be somebody else for a day, who would it be?

Scully:
Hopefully myself.

Mulder:
So boring! I mean, wouldn't you be tempted to try on somebody else's existence for a day, live your life as somebody else?

Scully:
Looking like someone else, Mulder, and being someone else are completely different things.

Mulder:
Well maybe it's not. I mean, everybody else around you would treat you like you were somebody else. I mean, ultimately, maybe it's other people's reactions to us who make us who we are.

Scully:
(pauses for a while as they walk, thinking) All right then. Eleanor Roosevelt.

Mulder:
(regretful) Ay. Can't be a dead person.

Scully:
(slightly annoyed) Why the hell not?

Mulder:
(as if it is a perfectly acceptable explanation) Because.