Complex sentence: As a practical joke, colleagues Barry and Matt phone Ben, and Matt pretends to be an art gallery owner who has seen some of and is interested in Ben's drawings and schedules an appointment at which Ben can present more drawings for evaluation.
Split into simpler sentences: As a practical joke, colleagues Barry and Matt phone Ben, and Matt pretends to be an art gallery owner who has seen some of and is interested in Ben's drawings. Matt, still masquerading as the gallery owner, schedules an appointment at which Ben can present more drawings for evaluation.