Complex sentence: Despite being a junior, Julie and her friends Perry Malinowski and Amber Regan went to McKinley's grad night; unbeknownst to Wendy, she and Perry board the Devil's Flight roller coaster.
Split into simpler sentences: Despite being a junior, Julie and her friends Perry Malinowski and Amber Regan went to McKinley's grad night. Unbeknownst to Wendy, she and Perry boarded the Devil's Flight roller coaster.