First comes the bad and boring riddle (the answer is to be written in all capital letters):
Magnesium plus Gallium yields a joke.
Next comes the easy alphametic:
Solve the answer to the bad and boring riddle as an alphametic.
(Every letter stands for a digit in base-10 representation, different letters stand for different digits, and leading digits are always non-zero.) Which digit does each letter represent? Please present the full analysis how these digits can be determined.