Synesthesia is a trait where two or more senses occur at the same time. For instance, when someone sees the color yellow they can hear a specific sound. This condition affects the neo cortex.
Brainstorm a list of sounds, tastes, and feelings. Walk around the room (or use the chat or breakout rooms if you're online) and ask people what image comes to mind when they hear one of your words.
For example, if I had the word tweet on my list, I would ask someone in the class what they see in their mind when they hear the word tweet.
Write down each response next to the associated word. Move around the room (or ask a variety of people via chat or breakout room if you're online) and try to get as many different responses for each of your words as possible.