The first thing any comedian does on getting an unscheduled laugh is to verify the state of his buttons.
Source: In W. C. Fields, Rowdy King of Comedy, by Robert L. Taylor.
-- W C Fields, (Jan 29 1880-1946), US actor, comedian; He was famous in vaudeville, stage, film and radio for hard drinking and dislike of children; starred with Mae West in My Little Chickadee, 1940.