1 Ishmael: You're a Martian agent, bent on letting Earth be destroyed! Help!
2 Man in Black: {appearing suddenly} There's no such thing as Martians.
3 Man in Black: Or any other strange unexplained phenomena you think you may be witnessing.
4 {silence as Man in Black vanishes as mysteriously as he appeared}

I like it when I can do visual gags. Most of my gags are dialogue-driven, so it's a nice change of pace for me when I can do something like this.

---

2020-12-19 Rerun commentary: I'm starting to wonder if maybe the Man in Black isn't a sort of Mr Snuffleupagus for Ishmael.

Although it looks like Loren is looking at him as well in panel 2. So who knows?