Complex sentence: Most of Vale's pranks are what he calls "pooter pranks", which involve Vale walking around in public making flatulence noises using a device he created, and capturing the victims' reactions on hidden camera.
Split into simpler sentences: Most of Vale's pranks are what he calls "pooter pranks". These involve Vale walking around in public making flatulence noises, using a device he created, and capturing the reactions of his victims on hidden camera.