Boyd had her first encounter with LSD in early 1965 when the couple's dentist, John Riley, secretly laced his guests' coffee with the drug during a dinner party at his home. As she was getting ready to leave with Harrison and John and Cynthia Lennon, Riley told them that he had spiked their drinks and tried to persuade them to stay. Outside, Boyd was in an agitated state from the drug and threatened to break a store window, but Harrison pulled her away. Later, when Boyd and her group were in a lift on their way up to the Ad Lib Club, they mistakenly believed it was on fire.