Silly Sac Horse. Give your child the ultimate fun backpack â the Stephen Joseph Silly Sac. Theyâre a plush animal and a bag in one! Each cute and cuddly design has plenty of room inside and they double up as a friend for hours of playtime too. What a great place to keep pajamas for an overnight stay, or to carry their swim kit in, or even a fluffy pal filled with packed lunch for a teddy bearâs picnic. Who wouldnât want a little buddy to carry all their belongings for them? Thereâs nothing silly about that!