I don't know that I have ever been able to successfully disconnect cu(1) on purpose.

You thought Vim was hard to quit, try to quit cu(1)

#freebsd

@rtyler BTDT ;) The secret is to give it a carriage return (or two) first *then* try ~.
@DianeBruce @rtyler And don't forget typing ~ *twice* if you're connected via ssh 🙈