The outing is business as well as pleasure, as it's part of Gnoth's job to monitor Terran popular entertainment to determine Yerethians are being represented fairly.
When that palls she thinks about boys, notably the two currently vying for her affection, the aggressive football hero Terry Blaine and the more gentlemanly intellectual Andy Dupas.
He has brought some records, and entices her into dancing, during which they accidentally bump the incubator, injuring Pat and eliciting odd sounds from the egg within.
At the Yerethians', the distracted teens fail to notice that the egg is hatching, and the baby alien, resembling a long-legged, long-necked alligator, emerging from the incubator.
The quick-thinking Andy attracts the baby's attention and ducks under a couch; it gets stuck trying to follow, and as it struggles he whips off his belt and chokes the creature with it.
At this point the parents arrive home; Triw gathers up her baby, clouting it into quiescence when it tries to bite her, while Gnoth sternly demands explanations.
"[4] De Camp also dealt with the theme of teens disrupting interplanetary relations in "Let's Have Fun" (1957), in which juvenile delinquents endanger the young of aliens rather than vice versa.