Questions of trivial relevance (e.g. "What kind of fruit would you be and why?") are actually not-so-trivial. There are several reasons schools ask such 'silly' questions.
1) Every Chef Does It Differently But Aren't All Doughnuts The Same?
Many interviewers will interview dozens if not hundreds of applicants. When reviewing applicants days later in committee, it may be incredibly challenging for interviewers to describe their encounters proficiently without mistaking one applicant for another. Adding questions requiring unique answers puts an interview with a name and improves accuracy in recall.
2) Warm Up With A Check Swing
Some interviewers take the approach that a trivial question be completely irrelevant just to get you to loosen up. Interviews are not supposed to be as formal as drinking tea with the Queen of England. Many applicants are wound up so high-strung that it is difficult to investigate their personality and character. A simple question, one which is often laughter inducing, can help an applicant relax with a "softball question".
3) Put You Through A Grinder
When you are on a roll and the interview seems overly rehearsed with canned answers, a question like this can throw an applicant off their game. Seasoned interviewers know when an applicant has rehearsed answers. A question like this can spark creativity and get an applicant to discard their gameplan. This is especially important given my last comment...
4) Wanna Get A Beer Later?
A significant component of any interview is the interviewer's knowledge that the prospective candidate seeks status as a potential colleague. They want to see character, wit, charm, creativity.... personality. At one point or another, during every interview, an interviewer thinks to oneself "do I see myself in a lab doing diabetic foot exams with this person?" or whether it would be fun to commiserate after exams at a favorite watering hole. Passing the initial screening to receive an interview already pre-qualifies most students, academically speaking, so all that is left is evaluating character and personality - two things difficult to accomplish in a paper application.
The best way to prepare for an interview is to a) research the school and program, being able to cite specific examples when asked questions about the school and be able to ask more specific questions about the school b) have a general non-rehearsed, free-form concept of "why pharmacy" and c) a good night's sleep and breakfast (recommend avoiding foods which induce flatulence). The best interviews are ones which rapidly devolve from question-answer to free-flowing conversations and I promise you precipitating a sulfurous odor capable of stripping the varnish off The Thing's footlocker will only bring tears to their eyes - and not the good kind!!!