Besides the notable absences of guys like Sal, Ken and Paul, Sunday’s season premiere of “Mad Men” was missing one more beloved character: Sally Draper’s lisp.

“What (a lisp) actually is, is a retained infantile misarticulation,” says Sam Chwat, who’s the director of New York Speech Improvement Services (and whose name, when said aloud, might make you sound like you have a speech impediment). Chwat's team specializes in helping people get over their lisps -- and people have all kinds of lisps, he says. Some substitute an "s" sound where a "z" should be (so hiss for his, herss for hers, etc), some whistle their "s's," but the one we're most familiar with is the interdental lisp, where the tongue comes too close to the teeth.

"The last of the 44 sounds to stabilize in any speech pattern is the "s," because it requires the most delicate positioning of the tongue vis-à-vis the palette," Chwat says, explaining why so many kiddos lisp. Most children who can hear grow out of it by age 7 or 8, but if it hasn't disappeared by then, they're probably stuck with it unless they enlist the help of a speech therapist, Chwat says.

Later in life, some people suddenly lisp when they're nervous, and Chwat says health problems like hearing loss, a stroke or Bell's palsy, a temporary form of facial paralysis, can suddenly have adults saying "th" when they meant "s."

Kiernan Shipka, the 10-year-old actress who plays Sally on the show, told the Los Angeles times last week that her lisp started to naturally fade away, and she worked with a speech coach to completely shake it. Good for her, but we admit we kind of mith it.

Were you teased for your lisp as a child? Or is your kid struggling with a lisp now? Tell us about it in the comments.

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