I'm kinda amused that the strongest one I came up with was Carter being scared of ladybugs.
I'm also amused at the thought of Reese being so flustered by Qdoba's setup (it's basically the Subway of Mexican-style restaurants) that he needs Leon to talk him through it. Maybe it's the part where he has to actually make decisions about what he wants.
The Harold & Root one is simple but heartfelt… and completely unspecific, so you could use it for practically any pair of characters in any fandom. Sigh.
Fusco helping Root put on an outfit for one of her aliases, that one's a little better.
Harold admitting to not liking a classical composer is… kinda a weak secret, but I could see how it's something he wouldn't normally tell people.
If you have any thoughts about other six-word scenes here, go ahead and post 'em in the comments! Might be fun to give it a shot.