From Cynthia Lennon‘s book, “John”:
“Along with the delights of fine wines and good food, we were introduced to cannabis. Joints were often produced at parties or even in clubs, and passed among those who fancied a ‘took’. The Beatles had first tried cannabis when Bob Dylan introduced them to it, on their original visit to America.
Bob had listened to the lyrics of ‘I Want to Hold Your Hand’ and, thinking one of the lines was ‘I get high’, had assumed that this was a reference to drug-taking and that the boys were seasoned users. When he mentioned this to John, he was told that the line was in fact ‘I can’t hide’ and that none of the Beatles had tried drugs of any kind. That was when Bob had offered to initiate them.
They’d all got stoned, fallen around the hotel room with the giggles and thought it was great. After that they smoked dope fairly regularly, using it recreationally in the same way that they’d have a drink to relax and unwind”.