It is bad to suppress laughter. It goes back down to your hips. – Author Unknown

For one seldom hears a genuine laugh nowadays, and much of the phraseology of laughter is a mere fashion of speech. There are many people whose sides have never ached from over-indulgence in the outward expression of mirth…. With some persons a wheeze or a chuckle is the utmost they can compass. – “Laughter,” in The Spectator for the week ending Saturday, January 19, 1889

Men show their character in nothing more clearly than by what they find laughable. – Anon.