In The Great Gatsby, why does Nick have to restrain his laughter when Gatsby says the following?He is "...trying to forget something very sad that...

Gatsby says this important quote to Nick in Chapter 4,
when he tells Nick about the "truth" of his background so that Nick will not be taken in
by the elaborate fictions he has heard about Gatsby and his rise to wealth. However, in
spite of Gatsby's protestations of veracity, it becomes clear that Gatsby is merely
spinning yet another fiction for the ears of Nick. Although Nick is not entirely sure,
what clinches his belief that Gatsby is lying is the following
phrase:

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"After that I lived like a young rajah in all
the capitals of Europe--Paris, Venice, Rome--collecting jewels, chiefly rubies, hunting
big game, painting a little, things for myself only, and trying to forget something very
sad that happened to me long
ago."

Note the obvious
rehearsed nature of this sentence. Firstly there is little "big game" in the cities of
Europe, nor are there many rubies to be found, except in shops. Nick has to "restrain
his laughter" because, as he says:

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The very phrases were worn so threadbare that
they evoked no image except that of a turbaned 'character' leaking sawdust at every pore
as he pursued a tiger through the Bois de
Boulogne.

Gatsby is so
concerned to perpetuate the mystique that surrounds him and to downplay his humble
origins that he shares this "truth" with Nick in confidence, only to spread yet
more clichés and ridiculous ideas, and it is only later on that Nick finds out the real
truth about Gatbsy's rise to wealth and fame.