The 'Grease!' actor - who has children Ella, 12, and Benjamin, two, with wife Kelly Preston - says the sweet drink reminds him of Christmas, and he loves the way different varieties from around the world have very different tastes.
He said: "It represents winter wonderlands, it represents Christmas. I've collected various types of cocoa from around the world."
He then showed talk show host Ellen DeGeneres a number of different types, explaining how Brazilian cocoa powder has a "hint of cinnamon and pepper" which differentiates it from types from other countries.
However, a seemingly unimpressed Ellen replied: "Smells like chocolate."
John, 58, went on to explain that people should be careful how they handle cocoa powder because any impurities from air or touch can affect its quality.
He said: "Never blow on it. Like a fine wine, it changes the quality of the chocolate. So, never, ever blow on it."
John was appearing on Ellen's show to promote his festive album with Olivia Newton John, 'This Christmas'. All proceeds from the record are going to charitable causes.
And the actor's share of the money will benefit the Jett Travolta Foundation - named in memory of his autistic son who died aged 16 after suffering a seizure in the Bahamas in January 2009 - and he hopes the organisation can support people dealing with similar conditions, as well as other handicapped and underprivileged kids.
He explained: "Autism and seizures are the least known areas of illnesses and I feel bad that there's so many people dealing with this and there are no answers for. So, I felt like starting a foundation that will help that. Plus, I widened it. It's also for handicapped children and the handicapped Olympics. It's also for underprivileged children. So I widened my purpose a bit there, too."
Olivia - who survived breast cancer - will give of all of her proceeds to her eponymous Cancer and Wellness Foundation.>