It's not just, you know, what you say that matters in a job interview. It's also, like, how you say it.

The use of slang and phrases such as "like" and "umm" can make job candidates appear uneducated or immature, says Mary Michael Hawkins, director of the career center at the University of Denver.

"It shows that they are not as prepared as they should be," she says.

Students' habitual use of the word "like," for instance, is something campus career-services professionals are trying to address, says Brenda Fabian, director of the Center for Career Services at Susquehanna University in Selinsgrove, Pa.

"Recent graduates and current students are penalized (by prospective employers) for using the word 'like.' Many of them don't even know they're using it since it's a part of their everyday language," she says.

Doug Hamilton, director of career counseling at Birmingham-Southern College in Birmingham, Ala., suggests mentally placing a period at the end of a sentence to "remind the speaker not to add unneeded phrases."

He urges students to listen to newscasters. "When I ask them why they think news anchors sound so professional, my point is that they never use these types of words — 'like' or 'you know' — to fill in between their lines or to begin their sentences."

Other slang to stay away from when interviewing for a job, according to the experts: "To tell you the truth." "Whatever." "Dude."