KRISTEN BELL who is possibly the cutest thing going, is a HUGE fan of sloths.  And yesterday on "The Ellen DeGeneres Show", she revealed that she FINALLY got to meet one over the summer.  For her 31st birthday, Kristen's fiancé DAX SHEPARD arranged to have a sloth attend her birthday party. She didn't know about it ahead of time, but when there was a knock on her door and Dax told her that it was her present, she somehow knew.  She told Ellen that she thought, quote, "There's a sloth near."  But Kristen got so overwhelmed with emotion that before she could even meet the sloth, she just laid down in her bed and burst into tears.  Luckily for us, Dax taped her meltdown . . . and she showed the footage on "Ellen".  Then Ellen almost made her cry again.