My dog has a bump or lump in his ear. What is it and is it serious?

I am sorry to hear about Toki! This could be something like a small tumor of the skin which has been scratched and traumatized. It could also be a small wound that has become infected or an insect bite that was infected. Without touching and examining the area we cannot determine exactly what it is, so I would recommend bringing Toki in for the vet to examine it. If it is an infection they will prescribe antibiotics, if it is a tumor then surgical removal may be needed if they are concerned it could be a more aggressive form, or monitoring if they feel it is benign.