Blue Bow Ties are an accessory for Pets in Creativerse. They were activated with update R45 on July 25th 2017.
You can find Blue Bow Ties solely and only occasionally in Treasure Chests that will spawn randomly in dark places in range of view of player-characters on all Creativerse-worlds.
While Blue Bow Ties and other Pet accessories can be found in all types of Treasure Chests from low tier Wood Treasure Chests (spawning on surface blocks only at night) to high tier Diamond Treasure Chests (spawning on corrupted blocks); you cannot obtain them from any Creatures, and they cannot be crafted.
Blue Bow Ties cannot be put into any quickslot nor placed directly into the gameworld, but they can be traded between players on the same gameworld and they count as a new discovery when found for the first time.
Similar to Top Hats you can put a Blue Bow Tie on one of your Pets by clicking your right moust button or typing "f" (as the default-key) while looking at your chosen Pet, and then either use right-click on the Bow Tie in your inventory/bag or drag & drop it from your inventory/bag into the lower accessory-slot in the Pet window with the slightly brighter colored neck.
When Pets are dismissed, they will drop a Loot Bag with all accessories that they have worn, and the typical animal loot of the according species. However, if Pets should vanish because of a bug, the pet accessories will be lost.