The Holiday From Hell

Sure, Frank Costanza's observance of Festivus was weird, but his holiday customs pale in comparison to the strange paganism
described by H.P. Lovecraft's narrator in the short story "The Festival":

As the steps and the passage grew broader, I heard another sound, the thin, whining mockery of a feeble flute, and suddenly there spread out before me the boundless vista of an inner world--a vast fungous shore litten by a belching column of sick greenish flame and washed by a wide oily river that flowed from abysses frightful and unsuspected to join the blackest gulfs of immemorial ocean.

Fainting and gasping, I looked at the unhallowed Erebus of titan toadstools, leprous fire and slimy water, and saw the cloaked throngs forming a semicircle around the blazing pillar.  It was the Yule-rite, older than man and fated to survive him; the primal rite of the solstice and of spring's promise beyond the snows; the rite of fire and evergreen, light and music.  And in the stygian grotto I saw them do the rite, and adore the sick pillar of flame, and throw into the water handfuls gouged out of the viscous vegetation which glittered green in the chloritic glare.  I saw this, and I saw something amorphously squatted far away from the light, piping noisomely on a flute, and as the thing piped I thought I heard noxious muffled flutterings in the foetid darkness where I could not see.  But what frightened me most was the flaming column, spouting volcanically from depths profound and inconceivable, casting no shadows as healthy flame should, and coating the nitrous stone with a nasty, venomous verdigris.  For in all that seething combustion no warmth lay, but only the clamminess of death and corruption.

So if you thought visiting your relatives was rough yesterday, just remember: somebody always has it worse.