I let Filbert call me it and then forgot how annoying I'd found nicknames in the older games. I told Chow and Peanut no when they asked if they could also call me it.
Big Top decided to bestow upon me the nickname of "Chap." I think it's pretty funny actually. It makes all the animals have English accents in my head. "Right-o chap. Catch me a proper river fish, eh wot!" Blathers isn't the only one anymore!!!
On a side note: I wish I could make them call me "Broseph." I'd be making Yes Man jokes all the time. Don't judge me.