L&D, Mermaid-Style

Jane is currently obsessed with mermaids.  Fortunately, her older sister has been able to answer important mermaid-related questions, such as the following:

Jane:  "How do mermaids have babies?" 

Margot:  "They puke them up.  Since, you know . . . they can't open their legs." 

Jane:  [silence] 

Margot:  "But sometimes they just burp up a fish."