Yes, sometimes I try out foreign accents and voices when alone in the car or the shower. It's how I prepare myself in case I'm plucked from obscurity to play a Bond villain.
When I am alone, I am a far gayer person than I am in polite company. I sing. I flex certain muscles and feel them to gauge their pumpitude. So, so lame. I recite dialogue from movies. And, if that dialogue requires a foreign accent, I definitely try and recreate that accent, or do an impression of the actor playing the role. I almost certainly suck at this, but it totally sounds good in my mind. "Not bad! I could pass for Irish, so long as everything I said was somehow a quote from Snatch!" I have been doing this alone in my bathroom when my wife will ask me what I was saying.
ME: I wasn't talking to anyone.
HER: I thought I heard something.
ME: Okay, I may have been talking… TO THE LORD.
HER: Oh, shut up.
Anyway, despite the fact that privately trying on voices has a definite dipshitty, young-Gwynnie-Paltrow-in-drama-class quality to it, I still do it. Because what if I AM the next Mel Blanc? You can't know that! (NOTE: You can.) In my experience, certain accents and voices are way more fun to talk in than others. And here are my top five:
There's a reason every fuckhead on Earth tries out the Irish accent on St. Patrick's Day. I particularly enjoy Daniel Day-Lewis' accent in In The Name Of The Father. MIND JAR MANNERS, YOU FOOKIN' PRECK!
2. Diamond Joe Quimby
Not a real Boston accent, which is stupid and grating. No, I mean the comically exaggerated mock Kennedy voice. I UH, ER UH, HAVE A HUGE HAHHHHHHHHHDON.
On the exterior, I'm all Mr. Asshole Comedy Snob and saying, "Pirate jokes? So passe." Then I get in the car and I'm like ARGH! YE SCURVY DOGS HAVE CUT ME OFF FOR THE LAST FATHOM! YE SHALL FIND ME PEGLEG IN YER RUMHOLE, MATEY!
4. Phil Leotardo gangster accent
"I gotta take a shit." "I guess the turd doesn't fall far from the faggot's ass." Much more enjoyable than doing the whole Brando thing.
It's like Walken. You just… speak haltingly… for a moment… AND THEN IN VERY LARGE BUSTS OF DRAMA.
Honorable mention to talking like a vampire (Lugosi style, not that Twilight crap), Cockney, pidgin Engrish ("This is not a chalade. We need totar concetlation."), Russian (one I did a lot more right after watching Eastern Promises), Cletus the Slack Jawed yokel redneck, and Sean Connery. Yours in the comments, er uh.