Even stars of Rose Byrne's caliber have to follow the rules.
In February, the 36-year-old actress welcomed her first son, Rocco, with her 46-year-old partner, actor Bobby Cannavale.
Rose has been traveling all over the country in the last few weeks to promote Universal Pictures' "Neighbors 2: Sorority Rising" and 20th Century Fox's "X-Men: Apocalypse." On Thursday, she stopped by CBS' "The Late Show With Stephen Colbert" in New York City, the show where Bobby had announced Rocco's birth.
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"He was extraordinarily tired when I talked to him," Stephen Colbert said.
Rose replied, "I was tired, too!"
"I know," Colbert said. "You did the bulk of the work here."
"Who needs sleep?" Rose joked. "You just roll on coffee and love."
One of the biggest lessons Rose has learned since becoming a mother is that time is not on her side — and it likely never will be.
"It takes a long time to leave the house, maybe an hour, hour and 45 minutes just to get out the door," the Australian actress said. "To do anything, you have to bring so many things with you: the bottle, the sling, this and that. Then when you get out, then he just throws up everywhere or takes a big poop, and you've got to go back inside again."
Sometimes she packs things she shouldn't.
"I've been doing a lot of traveling, too, so I've been taking my breast milk everywhere with me," Byrne said.
Stephen showed a photo of Byrne at the airport as her breast milk was confiscated by the TSA for being over the 3-oz limit.
"They wave this weird thing over the top of it and there's a whole production going on," Byrne said. "They take it very seriously that it could be something. I just stand there and smile and tell them that it's really breast milk and that it's nothing."
After Stephen suggested that all she had to do was point to Rocco, she joked: "'He's really real, he's here. You want me to get [my breasts] out?'"
No, Bryne won't really use her boobs to prove anything to the TSA.
"I'm not going to do that," she said. "No, no, no!"