Trust grows fastest through shared experience, so add an activity, like a walk, a game or a hot sauce challenge, to plain conversation.
The idea
Trust comes from shared context: a mutual friend, a community, shared values. Shared experience builds it even faster. Relationships grow face to face, and they grow faster side by side, doing something together. Intense experiences bond hardest (it's no coincidence fraternity pledges and military recruits suffer together), but ordinary ones count too. Slow service, a muddy trail, a terrible restaurant: any of it becomes common ground, and the more unusual, the better.
How to do it
Add an activity. Grab your coffee to-go and walk the neighborhood instead of sitting down.
Make it memorable: a new sport, an escape room, a ropes course, a board game.
Do it in groups. Shared group experiences multiply relationships quickly.
Invoke the memory later (see Script). When they remember it too, it pulls you closer.
Example
Fraternity hazing was the start of some of my most cherished lifelong friendships. I can go months or years without talking to those guys, and we carry on like no time has passed. I'm too old for hazing now, so I've occasionally hosted hot sauce competitions in my office instead. Shared experience plus shared pain: no one has forgotten those.
Script
"I was at a basketball game last night and I thought of that time we got schooled by a bunch of kids." "Went back to that restaurant we tried a few years ago. Still terrible!"
Watch out for
Overdoing the intensity. Plenty of the people you want to know can't handle ghost peppers.
Five Alternatives to Coffee: Instead of coffee: take a walk, go to their favorite spot, cowork, attend a talk together, or discuss one question in a small group.
Manufacture Shared Experiences: A slightly intense shared experience bonds people faster than polite chat, and even an event that goes wrong becomes a story you share.
Social Objects: Interactions revolve around shared objects, stories and details. Collect them and create them, because they become your reasons to connect.
The IRL vs. URL Test: Ask whether a meeting is for connection or a transaction; meet in person for the first, use video or a call for the second.