You add Hamster and Hippopotamus.Hippopotamus+Hamster. If it does not work try Hamster+Hippopotamus.
mink+chinchilla
Kangaroo and guppy
Ant + Scorpionfish
Android+bee
Dwarf+segacious
Raven + dove
Bear + snail
Ant + Eagle
tiger + pig
Horse + manul
Bat+alien
starfish + lion