If you search for character names on DuckDuckGo, there's a chance that the little icon of the duck mascot in the upper left will appear wearing of costume of them!

Some of the names that worked for me so far include Captain Hook, Peter Pan, Superman, Batman, Mad Hatter, Winnie the Pooh, and Ash Ketchum!

I don't know if this is a permanent thing or just a Halloween gag, but it's kind of fun to search random characters and see which ones the duck will dress up as!