The radioactive monkey was a chimp being used as a test animal in a government lab. One day, some PETA activists broke into the lab to free him, but one of them tripped, and knocked a vat of radioactive Spam into his cage. Moments after consuming the radioactive Spam, the chimp gained superhuman strength and intelligence. He broke out of his cage, killed and ate the PETA activists, and has been on the run ever since. He's being chased by men in black who work for super secret, off budget, black government agencies. Rumor has it that he long ago built his own spacecraft and escaped to the Moon, but this has never been substantiated.