The word "eggplant" actually makes sense if you have seen one variety of eggplants (if you can find pickled eggplants imported from Israel, for example) which do resemble eggs in their shape and size.

Shameful is still different from shameless, though both can mean bringing shame or "disgraceful". If I did something bad and then felt shame for doing that, I was "shameful" (full of shame, though this use is now a bit archaic). I would be shameless if I kicked the crutch from an old lady who was going to a cab she just hailed, took the cab myself, and did not say or feel sorry about what I did to the old lady. The same action could also be said to be shameless or shameful. Besides their apparent difference in degree when meaning disgraceful, shameful does not refer to the state of mind where one does not feel shame about his or her shameful deeds and when shameful does refer to a state of mind, it means the opposite of shameless.

Though inflammable can be synonymous with flammable in the sense of catching fire easily, inflammable can also mean easy to get angered (i.e., irascible), which meaning flammable does not have.

And native speakers apparently do say "a cup of hot coffee" though "a hot cup of coffee" appears to have higher frequency in use.