Every episode:
Mulder: Scully it was aliens
Scully: No Mulder it wasn't aliens
Mulder: Look, an alien!
Scully: No Mulder aliens aren't real
Mulder: Scully there is literally one standing next to you and waving
Scully: Hmm, maybe but I'm not fully convinced
That's it, that's every episode. And I love it
Mulder and Scully are the only FBI agents I will never cancel.