Co-writing is scary because you have to say your bad ideas out loud. That’s also why it works.

Alone, you edit before anyone hears anything, which keeps you safe and also keeps the half-formed idea from ever being tested. With someone else in the room, the bad idea has to leave your mouth, and more often than not it turns into something neither of you would have reached alone. The embarrassment is the toll on the useful road.

Write with one person for an hour and agree beforehand that nothing is judged for the first twenty minutes. Say the obvious option, the stupid option, the one that rhymes badly. Keep a list of what the two of you built out of the rejects.