They may have used that line in The Big Lebowski, but it’s been around a lot longer than the movie. I first heard it in the sixties, along with its corollary, “Is a bear Catholic?”.
I haven’t read through the whole thread, yet, so if this is a dupe, well…kiss mah grits! 
[very busy] Up to his a$$ in alligators.
She had a c**t that looked like chewbacca after a fight
Gotta be a damn gnuuuuu yolk yankee ta preciate dis one heah;
If… I’ll kiss your ass in Macy’s window on Christams Eve with the Salvation Army Band playin Amazing Grace!
And an Italian from Brooklyn or the Bronx for these:
fuhgeddaboutit!
he's takin a doirt nap,
he sleeps with the fish,
get lost!
Va fongoool (go fuck yourself)
a gooola du sord (your sister's ass)
get the fuck outta here!Yay!!! That’s my .sig!!! 
Yay!!! That’s my .sig!!!
doh! Double post…sorry.
Oh, my grandmother has some real beauties:
Happier than a dead pig in the sunshine
Nervous as a long tailed cat in a room full of rocking chairs
and, if something was crooked or messed up, it was ‘whomperjawed’…possibly ‘caddywhompus’.
She’s not a woman, she’s a funnelweb in a frock!
(From “Grassroots”, an Oz sitcom about a rural local council)
Yer blood’s worth bottling! (You, sir, are a gentleman and a scholar!)
Fair dinkum, I’ve only once heard anybody say “Fair dinkum”.
“I wouldn’t trade my grandmother’s toenails for that <insert item here>.”
“Heavens to mergatroid.” (mergatroid??)
About a cute boss:
Remember; an (terminal digestive port) with nice buns is still an (terminal digestive port.)
I really hope I didn’t post that earlier in this thread.
I think that “Heavens to Murgatroyd” thing was the catch line of a long-ago Hanna-Barbera cartoon character. I can’t remember which one.
Mine are always of the format:
‘The ‘adjectivest’ ‘noun’ since sliced bread.’
(The hottest day since sliced bread. The oldest man since sliced bread. The most famous film since sliced bread…)
Sliced bread has been a lot of things.
-J
Hmmm, Zenpea…I’ve only heard “sliced bread” applied to clever/handy/nifty/wonderful things–“the greatest thing since sliced bread”. Since pre-sliced bread is a nice improvement over unsliced bread. The “hottest day”??? Just doesn’t make sense.
(I heard a variation recently—“greatest thing since pants with pockets”).
My father in law says: “Well, I’ll be a suck-egg mule.”
I think that came from a western or something…
Here’s a classic from MST3k: “If her pants were any tighter, they’d be behind her.”
Having a smoking section in a restaurant is like having a non-peeing end of the pool.
He has a 10 story head with an 8 story elevator.
On farting:
There’s a mouse on a motorcycle
On pooping:
There’s a southbound train with no brakes.
Or the Shanghai express.
Just heard one in training this a.m.:
“He was stuck on stupid and dragging ignorant!”
When I worked in Texas my boss had a long list of colloquialisms .
I hope when you get home your Mama runs out from under the front porch, and bites you on the leg.
I hope a bolt of lightning hits you so hard there ain’t nothin’ left but a smokin’ hole in the ground.
If I ever find myself missing you I can always reload.
You lie like a dog.
He’d say “He’s rich as nine feet up a bulls a$$.”
When I asked him what he meant he said, “When you get nine feet up a bulls a$$, it starts gettin’ mighty RICH.”.
She thinks that she got a goldplated a$$hole.
She’s got curves in places that a lotta women ain’t even got places.
She looks good enough to make a preacher leave home.
My boss believed in quality, over quantity. He’d say " When you get to the end of a row of cotton, that’s all there is to pick." He didn’t want us to run out of work.
More fun than a bootfull of barbwire.
I’d beat you in a race, and I’d only be runnin’ on one leg half the time.
When talking about porn, or nude clubs, “Just because you’re on a diet, don’t mean you can’t look at the menu.”.
Boy, I was doing this when y’all was still XXXXoff to the underwear section in Sears catalog.
When giving directions, “First, y’all head down yonder a piece as the crow flies.”
Divorce is like a pay toilet. You have to pay to get rid of something you can’t keep.
Our Gov’mint is just the opposite. They make you pay for $hit you don’t want.
In 8 years that’s just a tiny fraction of his east Texas wisdom.
Put THAT in your jockstrap and snap it.
not exactly southern but…
She has a face that can sour boiled water
She could suck start a harley
You don’t look at the mantle piece when you’re stoking the fire
Cold as a well digger’s ass
Ain’t got a pot to piss in, or a window to throw it out of.
Grinnin’ like a possum eating shit out of a Coke bottle.
I’ll sink you like a three foot pipe.
Busier than a one-legged man in a butt kicking contest.
I’ll slap you so hard your kids’ll be born dizzy.
I remember “Serious as a bee sting and three heart attacks.”
Also “It’s hot enough to fry the devil.”