The African Helmeted Turtle
Talk about a squee factory! This species' trademark smile is the friendliest in the animal kingdom. To make matters even cuter, when a male wants to find his soul mate, he respectfully nods at some choice ladies. The gals who aren't interested will snap at him, and leave him hanging like total jerks. But Mrs. Right will nod back at him and if the pair ends up mating, they'll nod in approval together the whole time too. Cuteness = off the charts.