you can use this word in pretty much any context and it will make you sound pretentious and/or confuse the person you're talking to.
it's a technique refined and highly over-utilized by pseudo-intellectuals
"thoughts of existentialism breezed through my cavern of a mind as i walked under the concave arches in the courtyard of my prestigious university."
"there i was, caught in an existential dilemma. i decided to run the red light."
"i felt that the existentialist undertones in the simpsons represented the decay of religion in society."