Spoiler Alert: Humor and punchlines will be explained.
HEALTH Are you the life of the party or an outsider looking in? Humor is subjective, largely because everyone's brain is wired differently. Word associations are reinforced by a repetition of each individual's unique life experiences. Someone who reacts differently may not have formed similar enough synapses in the brain.
I have fond and funny memories of swimming. But someone who nearly drowned in a river or experienced some other traumatic event might recoil at the very word, "swim." Personal experiences have an effect on the reaction to religious, political and racial innuendo, as Michael Richards painfully discovered. A joke that relies upon profanity is depreciated in the minds of those with high morals.
A person with an artistic background may subconsciously convert words to images. An English teacher might analyze the grammar of phrases. Someone hearing a joke in a language that is not their mother tongue may have a literal word interpretation. During conversations, a linguist likely performs translations in the back of his mind.
As a result of our cultural influences, we hear the same words from different perspectives. Hence, in a crowded room, some might react with outbursts of laughter while others just smile and another puzzled group responds, "I don't get it."
During an interview with The Joke's on Me author Laurie Boris at one my new favorite websites, Facing 50 With Humour,  Laurie told the following joke:
Q: What do you get when you cross a kangaroo with an elephant?
A: Great big holes in Australia.
Did you laugh? To me this is funny—not LOL funny but humorous nonetheless. I shared it with a group during dinner the other day. After the punchline, it was enlightening to hear one deadpan response: "There are no elephants in Australia." Our minds had totally different reactions to the same words.
The initial question leads me to anticipate an incongruent answer. The punchline conjures in my mind the diameter of an elephant's foot. I see him uncharacteristically jumping about and the resulting path of destruction. I appreciate the unanticipated geographical transport to Australia associated with the kangaroo. My mind created visuals of nearly every word, without need to explain the joke — as another person in the group attempted to demonstrate with dramatic gestures.
I enjoy jokes similar to that told by Laurie. Words and punchline alternate between double entendre (often seen in some of the blog titles here), homonyms, synonyms and visuals. In this respect, much of the amusement takes place in the mind of the listener. Do you get the next one?
What kind of name is Starbucks for a coffee house? Few deer have become stars.
And if I wanted to drink coffee with Bambi, I would not have become a vegetarian.
If you smiled, it's my original joke. If not, I got it from someone else. Again, my mind is flooded with visuals. It's often said that if you have to explain a joke, it's not funny. Excuse me for breaking this rule: The humor zeroed in on "deer" as a synonym for "buck." Before the comma in the third sentence, one might visualize a person sitting at a table drinking coffee with deer in the room. The punchline occurs after the comma, when a beloved character is transformed to deer meat on a plate. Did your mind make such visual associations or was it blank? Perhaps you more readily associate "buck" with currency, are not aware of that "buck" is a male deer or maybe you've never been to any of the 50 countries with Starbucks coffee shops.
Some who prefer sophomoric or slapstick comedy might consider subtle incongruity too dry to be humorous. British humor is notoriously dry in comparison to Hollywood comedy. I can appreciate some subtle cerebral stimulation. A sense of pleasure may be felt without literally ROFLOL. It is often argued that one of the most common differences between the British and American sense of humor is that Americans don’t understand irony.  There are other reasons why some people are disinclined to laugh. Patients with early signs of dementia may be incapable of detecting sarcasm. Stoics do not generally see much in life to smile about.
Dr. Shock attempts to answer the question of where humor resides in the brain. There is a broad consensus of the exact meaning of the terms 'laughter,' 'humor' and 'funny.' The complex reaction to humor is mainly described as a two-phase response called the incongruity theory. 
According to the incongruity theory, humor involves the perception of incongruity or paradox in a playful context. For something to be funny, two stages can be distinguished in the processing of humorous material. In the first stage, …the perceiver finds his expectation about the text disconfirmed by the ending of the joke… In other words, the recipent encounters an incongruity—the punchline. In the second stage, the perceiver engages in a form of problem-solving to find a cognitive rule which makes the punchline follow from the main part of the joke and reconciles the incongruous parts. Other researchers have called these stages 'surprise' and 'coherence.'
Did you follow that? Basically, humor is perceived when there are parts of a story that reconcile, though in an unanticipated manner. There's a moment of surprise, immediately followed by coherence. In an non-humorous bit, the listener may be surprised without coherence.
Do you have a funny bone? Sarcastically, it has been said that some don't have a funny bone in their bodies. What about you? Anatomically, the ulnar nerve is trapped between the humerus bone and the overlying skin when the elbow is bent. Striking the elbow (medial epicondyle) in this position is commonly referred to as bumping one's "funny bone." This name is thought to be a pun, based on the sound resemblance between the name of the bone of the upper arm, the "humerus" and the word "humorous." Alternatively, according to the Oxford English Dictionary, it may refer to "the peculiar sensation experienced when it is struck." 
Do You Have A Sense of Humor?
If you find yourself 'not getting' a joke or telling one that is not well received, the comedian may not be at fault (though often this is the case). Some people require more clues or breadcrumbs leading to the punchline. Linguists and scientists have expended considerable effort attempting to define humor. Our life experiences are different. As we associate more with people and expand our understanding of different cultures through literature and conversation, we will form enough synapses to finally "get it."
Humor can be therapeutic. The American Cancer Society defines laughter therapy as "the use of humor for the relief of physical or emotional pain and stress."  A good laugh releases endorphins and provides moderate muscle contractions. Learn to see situations from different perspectives. Leave your favorite joke in the comments below. Don't take yourself too seriously and you'll stay A Bit More Healthy.