Cats get really bothered when people accidently touch their whiskers. The reason: whiskers are highly sensitive, and cats rely heavily on them.
When it's dark, for example, whiskers help cats determine whether they can fit into cramped spaces - such as the area between a person's chin and chest while sleeping.Whiskers also function as wind detectors. Working with a feline's acute sense of smell, they help locate the source of an odor. Unsubstantiated studies also indicate whiskers are particularly sensitive to the drafts created by hot tuna casseroles.
Most amazingly, whiskers protect a cat's eyes when it's plunging through the undergrowth. Each time a protruding branch or bent twig touches the cat's whiskers, it triggers an astonishingly fast eye blink.
A cat would be lost without its whiskers. So, never trim them or cut them off. Periodically, they'll fall out on their own. But new ones take months to grow back.