I had a history teach in my local community college say that we got the word commode because the reign of Commodus was so bad it reminded people of human waste. I didn't believe it at the time and I've never heard that before and I've never heard it since. Any truth to it?
No.
As a general rule, it's good to be skeptical of etymologies that seem too pat, or too funny, or too convenient.
The word is first attested in the 1680's and referred to the wire frame that underlay a kind of woman's headdress worn in France. The name is based on the French word commode (meaning "convenient", which in term comes from Latin "commodus" which meant "proper, convenient, satisfactory"). About a hundred years later, it was being used to refer to a variety of small cabinet-like pieces of furniture. From there, we get to a small toilet that could be moved around, and which was used for people who were unable to get to one on their own. This usage is first attested in 1851, and again is a reference to the "convenience" element.
Sources: Encyclopedia Brittanica article linked above, plus the Harper Collins Online Etymology Dictionary.