In the first Neighbors movie, Rose Byrne's character, Kelly, has a breast milk incident. After a night of partying, Kelly's breasts are painfully engorged, but a broken pump means her husband Mac (Seth Rogen) has to help her get the liquid out. It sprays everywhere.As far as we know, Byrne's own experiences haven't been nearly that traumatizing, but new motherhood hasn't been without any mishaps. The actress has, after all, had her breast milk confiscated by the TSA.During Byrne's appearance on The Late Show With Stephen Colbert to promote Neighbors 2: Sorority Rising, the host pulled out a photo of a surprisingly cheery Byrne holding up a bottle at an airport security check. "They wave this weird thing over the top of it, and there's a whole production going on," Byrne explained. In response to Colbert's inquiry as to what her move is while this is happening, Byrne said: "I just stand there and smile and tell them it's really breast milk."Byrne gave birth to Rocco, her son with partner Bobby Cannavale, earlier this year