And “euphonious” is quite… uh, what’s the word? It sounds nice, at any rate.
I like:
Pleonasm
Majuscule
and of course, this combination:
Hot Fudge Sundae
[Entenmann’s] Rich Frosted Doughnut
Actually, you can go further with that one, and still have a grammatically correct and readily parsable sentence:
Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo.
One I’ve fancied since childhood is “I’d’ve,” which I have always enjoyed for its having two apostrophes. Not too many other contractions can claim that pedigree (I can only think of one other, “wouldn’t’ve,” which just feels sloppy).
Ahhh… this is obviously some strange use of the word readily that I wasn’t previously aware of.
I’ven’t a clue what you mean by that. There are also some in naval use, such as “Bo’s’n” (“Boatswain”) and “Fo’c’sle” (“Forecastle”).
jackdavinci, how can you mention “autokinetikon” without its partner, “ipsemobile”?
And I’ll add “tintinnabulation” (the sound of bells) to the list. It just trips off the tongue. “Hemidemisemiquaver” (a sixty-fourth note) is also fun. Or, heck, even just “quaver” (an eighth note). “Plectrum” (the part of a harpsichord which plucks the strings) works, too.
I was tickled to discover, via the Moot ™ game, that the plural of Charisma is Charismata.
Ah, the onus of celebrity.
Why stop there? Try a semihemidemisemiquaver for size. 
A contradictory oxymoron is a tautology.
(Of course a repetitive tautology is an oxymoron.)
Episcopalian Anchorite. Actually, Episcopalian is probably my favorite word to say out loud just on its own. If I ever go back to religion, I’m gonna become Episcopalian just so I can say it all the time. I’ll even introduce myself that way - “Hi, I’m pprgrl, and I’m an Episcopalian.” Episcopalian episcopalian episcopalian!
“Episcopalian, savin’ all my love for you!”
– Bill Bryson (I think)
Ooo, cool.
Dogma → dogmas or dogmata
Stigma → stigmata
Magma → magmas or magmata
Smegma → no plural given
Thanks for sending me exploring!
Well and good. But will you be a didactic Episcopalian? 
The Onion included “titular archbishopric” in its list of words that sound dirty but really aren’t.
dialectic pugilism
As in, "Don’t EVEN ATTEMPT to engage ME in dialectic pugilism 'cause you’re out of your league and you’ll end up getting your ASS kicked, laying on the floor, kicking and screaming, and crying for your mommy. Got it, SMARTASS!!!
I’ve always liked the word ‘plummet’.
Cheque enclosed.
toy boat
Bosky zarf.
We named a nearby stray cat with this appellation after one too many rounds of Scrabble. (So the cat’s name means “a small stand for a hot beverage, surrounded by bushes.”)
The German word for nurse - Krankenschwester. It makes me laugh for some reason. I’m easily amused.