Astro has so many nicknames. Walrus, Hippo, Wrinkle, Wrinkle-face, Lil Wrinkle, Drool Face, Drooly Puppy, Fluffbutt, and Bubs, to name the most used ones. He responds to "wrinkle!" as much as to his actual name.
I tend to only use his name for training and recalls, and it has a lot of potency. All other times, it's a nickname.