It’s so easy to become cynical about comedy. “Make me laugh” is the defiant challenge of visitors to improv clubs from Manhattan to Manhattan Beach. But there’s only one place that can make me laugh against my will — even if the world happens to be ending, whether literally or figuratively. Born of the anti-Establishment satire of the early 1960s, the Groundlings theater group has survived 33 years of personality clashes, migrating venues and money crunches to turn out an ever-growing roster of comedy luminaries, including Phil Hartman, Cheryl Hines, Will Ferrell and Kathy Griffin. (Almost from the start the Groundlings have been an informal talent trout farm for Saturday Night Live.) For my money (not that anyone will be taking it on doomsday) the Groundlings are at their best in their weekend sketch-comedy shows, during which they also flash brief improv segments. The Groundlings’ secret lies in its members’ ability to look inward and locate the shadows that haunt our daily lives. We the audience recognize these darker uncertainties of existence that normally frighten us and laugh at them instead. Gentle, apolitical and vaguely suburban in their outlook, Groundlings sketches celebrate the plight of the “put-upon” American — a sane and tolerant person who finds him or herself engulfed in an insane and disagreeable situation that grows more extreme with each line of dialogue.