'Sesame Street' Look Who's On!

Charlize Theron, Halle Berry, Joseph Gordon-Levitt, and more stars visit in upcoming season 43 (debuting Sept. 24); we've got pics of their April visits to the set, plus inside dish on the segments.
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Joseph Gordon-Levitt

The Looper star (who — awwww! — brought along his mom) got quite a primal rush while teaching the word reinforce to Murray. ''There's a definite opportunity for proper Three Stooges moment here,'' he told the director about the skit where Murray bangs and bangs and bangs a well-reinforced box containing the actor's prized watch.

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Charlize Theron

When the Snow White and the Huntsman
star wasn't showing off her son, Jackson (who was adopted just weeks
earlier), to Elmo, she was teaching Abby Cadabby about the word jealous.
As in, even Oscar winners get jealous of fairy wings.
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Paula Patton

"I never thought they'd ask me,'' says the actress (seen here primping
Abby), who couldn't stop beaming about being invited to act out the word
innovation alongside a futuristic Elmo and a robot. ''I don't really look at [Kevin Clash]. I just focus on the furry little red guy.''
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Kristen Bell

House of Lies star got the word splatter,
which meant take after take of pretending to have ketchup and mustard
thrown on her. ''I told Kristen maybe we should make a video with [Elmo]
for our future kids,'' says Bell's fiancé, Dax Shepard, who did his
skit the following day. ''Hopefully they'll let me come back. They've
been around for 43 seasons. I think they'll still be around then.''
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Eric Stonestreet

''It's the easiest yes to say in the business,'' the Modern Family actor tells EW after shooting a segment with Abby about the word remember.
During filming, Stonestreet worried that his face was too sweaty. ''Am I
too salty?'' he asked Abby's puppeteer, Leslie Carrara-Rudolph.
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Halle Berry

The Oscar winner showed her strong improvisational skills when she got the word
nibble at the last minute, pretending to be scared of a t-t-t-t-tiger that takes a delicate bite of pizza.
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Timothy Olyphant

Surprised to see the usually stony Justified star smiling?
He wasn't the only one who couldn't keep a straight face when acting opposite the Sesame Street
cast. ''I love watching celebrities come to Sesame Street,'' says Kevin
Clash. ''Their eyes turn into 5-year-olds. You can tell it's special to
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Dax Shepard

The Parenthood
star was all too happy to step in when Nathan Fillion had to pull out
because of an injury. ''I would put this up there with being on [The
Late Show with David] Letterman. I watched that every night as a
kid. The idea I would be on there was inconceivable. I'm maybe one
appearance away from retiring.''
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Don Cheadle

The House of Lies
star joked about how he found out which puppet he'd be teaching the
word ''inflate.'' Said the Oscar nominee, ''I said, 'who's the puppet?'
Cause I have standards. I'm not gonna be with just any puppet like
Oscar. I don't need that negativity this early in the morning. They said
'Elmo' and I said, 'yeah! He's the star!'''
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Jon Hamm

Says Kevin Clash, the puppeteer behind Elmo, ''Jon Hamm was unbelievable. He was so funny. His timing was great.''
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Melissa McCarthy

puppeteer Kevin Clash was completely taken with Melissa McCarthy: ''I
think the world of her. She's just a funny lady. I loved her spirit and
her joy. Hopefully we'll get to work with her again. She was adding all
these dance moves we hadn't even written for her."