The photo in question (or one like it):
Me: So what's that?
Hubby: It's a macrophage.
Me: Oh. Cool! [I didn't really say cool. I don't think I ever say cool]. What's that?
Hubby: It's a cell that eats stuff all the time.
Me: So if you were a cell, you'd want to be a macrophage? [I deduce this because what man doesn't love to eat?].
Hubby: [Ponders this seriously]. No. I think I would be a NK cell.
Hubby: NK! Natural Killer. They kill cells that would become viruses and tumors.
Me: Oh. Right. Of course. So. What kind of cell would I be?
Hubby: You would be a B-Cell.
Me: Why's that?
Hubby: [medical mumbo-jumbo which I translated into this] They are really organized.
Only a medical couple. Only.