I can’t seem to say “MacPherson strut” or “photon” without attempting a Scottish accent. It’s not an accent I do very well, either.
What about you? Are there things you can’t seem to say without extruding it through somebody else’s accent?
Thanks to a Philosophy professor from Scotland there is no way I can say ‘A Priori’ or ‘A Posteriori’* without an exaggerated Scotch accent and trill. A pr-r-r-r-r-r-ior-r-r-r-r–ri
*[sub]sadly there are very few contexts in which you get to say those without looking like a mega-pretentious douche[/sub]
“Fabulous.”
“Moose and Squirrel” in a Pottsylvanian accent
Most Mexican food.
Most French terms in my AP Euro class. Then I repeat the word in Redneck so the kids know how to spell it. 
“You might, rabbit, you might” as an Irish cop.
“Disgusting” as Paul Lynde.
If I’m required to count out a small number of items for someone because they’re being a dick.
One. Ah ah ah. Two. Ah ah ah…
I have no idea why I started saying “naughty” in a bad, vaguely English accent, but I keep doing it.
“Gilbert’s syndrome”.
Since Gilbert was french, I always pronounce it “jeelbear’s”. Or some such.
Confuses the hell out of the medical students. 
'El-lo!! Pretty much my version of Jon Stewart’s version of the Queen, saying something that I doubt she ever said.
My 7 year old daughter always says banana with a faux-einglish accent. Like “Bahhh nahhh nahhh”
My Mother in law and sister in law trained her to do this when she was about 3. They still think it is hysterical. Me not so much, but it is their in-joke so I don’t try to stop her.
Gotta be Austin Powers’ fault.
The name of any country or place. A friend from Nicaragua once spent an hour demanding that I learn to pronounce his country name properly. Since then it’s become a “thing” with me to pornounce them as the natives do. . . as much as possible.
"Room Key " in the manner of inspector Clouseau
Oh my god.
“I’ll be back” and “It’s not a toomah!”, Arnold-like.
“Isabella Rossalini” in a cartoonish Italian accent.
Likewise “Ricar-r-r-rdo Montalban” in an exaggerated suave Latin accent.
NeekaRWHAAAAAqgghwwaaa ending in a slight throat clearing (at least when I try to pronounce it correctly).
I can’t say “Corinthian leather” without trying to sound like a suave Spaniard.
(A linguist friend of mine said that one of the trials of being a linguist is that people always expect you to pronounce foreign words correctly, even if you don’t speak the language.)
That’s how I say “Not any more.”
I am almost totally incapable of saying the name “Juan” without the sexy-Spanish-lover accent. Instead of “wahn,” I am compelled to say “hhhhhhhhhhhhhhhhhhhhhhhhwAHHHn.”
The word “homage.” I don’t know why, but this always comes out with a French-chef-from-The-Little-Mermaid accent. Instead of “HAH-midge,” it comes out as “oh-MAZGGGGHHH.”
Al-you-minium.
When I hear “Murder,” my mind then pops “Most foul” in at the end… in a very odd voice, of which, I’m not sure whence it comes from.
Oh, yeah, I do that too. Since my wife has never seen the movie, she looks at me like I’m an idiot.