Because of the way Ben died, by drowning, his lungs are rather weak which results in him having a sort of breathless laugh and usually wheezes when he runs. You can also hear the slosh of water in his lungs that remained there even after death. This was found out when Tim picked Ben up one day and heard the sound.

YOU ARE READING
My creepypasta headcanons
FanfictionThese are my headcanons, not actual facts. Please dont harrass me about 'oh they dont do this or that'. They dont. Their just my opinion. Hope you enjoy.