He is Queen Delightful's dog who does tricks. Instead of doggy treats, he enjoys pickle treats, as does Queen Delightful. Sir Yipsalot gets his name from the yipping sounds he makes going, "Yip, yip, yip!"
According to Queen Delightful, Sir Yipsalot is well behaved but only in the right hands. In the wrong hands he can be very destructive and a major handful as Hildy and Grim found out when they held him for ransom against the Queen.