The phrase "I Know What You Did Last Summer 20" seems to refer to the 2025 American slasher film "I Know What You Did Last Summer," which is the fourth installment in the franchise. It is a sequel to "I Still Know What You Did Last Summer" (1998) and takes place 27 years after the events of the second film. The plot involves a group of friends who covered up a fatal car crash from the previous summer and are now being targeted one year later by a killer. The film was released in 2025 and includes some original cast members with new actors joining the story. If the "20" refers to the year 2020 or something else related, please clarify for more targeted information. For now, the main relevant info is about the 2025 film with this title.