One of which is to not take the suggestion literally.
If someone suggests banana, please do not eat a banana. If someone suggestions bathroom, do not take a mimed dump onstage. I'd forgotten the impulses to jump from one word immediately to the first thing I think of: that's what the audience does. When they say cake, they think in their heads "Oh my gosh, I love cake. I wish I was eating cake." But they don't really want to see a scene with a character who has a train of thought like that. You've gotta be one step ahead of your audience.
Literally, take the suggestion one step ahead of your audience. I take the suggestion (A) and think to myself: (A) makes me think of (B). Then, I think (B) makes me think of (C) and then take (C) as my suggestion to start the scene. If I get the suggestion cheese, I might think cheese makes me think of mouse which makes me think of eeek. I can take the idea of eeek and let it inform my character's voice or her personality or the fact that she makes people go eek. Whatever, so long as I'm not talking about cheese and how it's got holes.
Tonight is the second practice of the inaugural NSU improv team. We're running this exact exercise:
A to C
warmup: Get the team in a circle. We'll be free associating with words. Each person will take the word they're given (A) and say what it makes them think of (B) and then say what (B) makes them think of (C).
Someone starts with a suggestion, paperclip. Next Ryan says, paperclips make me think of offices and offices make me think of short skirts. Shannon says, short skirts make me think of the 80s and the 80s makes me think of Back to the Future. And so on.
exercise: Two people up. Get a suggestion. Each player will take the suggestion and do their own A to B, B to C thinking aloud. Then do a scene.
Suggestion is cab. Trey says, cab makes me think of New York City and New York City makes me think of pizza. Meg says, cab makes me think of driver which makes me think of Driving Miss Daisy. So then Trey starts the scene with a pizza boy character and Meg plays an old lady. Or whatever.
play: Two people up, standing back to back. Get a suggestion. Each player makes the A to C jump in their head. At the director's call, players turn to face each other and initiate at the same time. Then deal with it in a scene.
You get it. It's fun after these scenes (for the players watching) to guess the line of thought.
takeaway: It doesn't matter what you think of, as long as you think of something. There's no wrong way to free associate. The audience is smart, but they don't know it. When you go from cheese to eek, the audience will follow you. They might not see the mouse connection, but maybe they thought mold, or maybe they thought dairy farmer. It doesn't matter. We're there, and we're there by pattern. Like Bryan says, pattern never fails.