Lightning forms the same way, but it’s hard for us to study. Much of what we know about lightning is still theory as opposed to hard fact that can be observed and replicated. Positive and negative charges build up in clouds just like you built up charges on the balloon and in your hair. We believe these charges come from all the different ice fragments rubbing together and moving around inside a cloud. The cloud just wants everything to be even - positive and negative charges all mixed together instead of separated. This is why cloud-to-cloud lightning is more common than cloud-to-ground lightning, because much of this difference in charge distribution can be solved between clouds. Sometimes, though, charges also build up in the ground and in objects on the ground and it’s easier for the cloud to discharge through those objects than through another cloud. That’s what you just did - the balloon wanted all its charges to be even, so it discharged them through the spoon and now all pieces are neutral again.