The sound of an infant's laughter will warm even the coldest of hearts. But there's no telling what a sleep-giggling baby will do to the unsuspecting curmudgeon, let alone your average baby-nibbling human. I imagine it's akin to a Lisa Frank Trapper Keeper coming to life (unicorns, rainbows, puppies, oh my!).

But — fun fact — it's totally normal for newborns to laugh in their sleep. A 2004 study found that infants as young as 17 days were having the giggles during nap time. The real mystery, however, is what a 17-day-old baby could possibly find funny given its limited understanding of the world. Science, your move.