What kind of feeling were you having when you were laughing? Positive? Diabolical? Negative?
What was the punchline? The reason for the laughter to start. Amazement?
I have laughed in disbelief. I would see something and "HA!!!" This can't exist! This can't exist!! HAHAHAHAHAHAHA!! From feeling of disbelief, to shock, and to almost horror. I have also laughed with tremendous joy. It feels so good you don't want to stop.
Why do you think you were laughing uncontrollably?
"In the universe there is an immeasurable, indescribable force which shamans call intent, and absolutely everything that exists in the entire cosmos is attached to intent by a connecting link." ~Carlos Castaneda