Faster’n a jackrabbit on a date
… got any more?
Rainin’ harder than a cow pissin’ on a flat rock.
Slicker than snot on a glass doorknob.
Slicker than cat shit on linoleum.
Cute as a speckled pup in a collard patch.
Busier’n a one-legged man in an ass-kickin’ contest.
Dug in like a tick on a kid
(…for something stuck and hard to get out of wherever it is. I think I heard it in a movie once.)
Colder’n a witch’s tit.
Cold enough to freeze the balls off a brass monkey.
(Missed these obvious ones in the OP)
Sticks like snot to a blanket.
Slicker than whale shit.
Sharp as a marble.
Lower than whale shit.
Dumb as a sackful of doorknobs.
Dear ol’ dad saying - “It’s slicker than a cat’s ass and twice as nasty”
Slicker than snot on a hoe handle.
Dumber than a box of rocks.
Dumber than a sack of hair.
Not the sharpest tool in the shed.
Not the sharpest knife in the drawer.
His elevator doesn’t go all the way to the top.
Her cheese done slipped off her cracker.
Colder than a well digger’s butt. Or shovel.
Hotter than a whore house on nickle night.
As cold as a warlock’s cock in a brass jock.
I’m [sweating like] / [nervous as] a whore in church.
and finally, one I’m pretty sure I picked up the straight dope…
You’re uglier than a bucket of assholes.
Sweating like a hen drawing rails. (No idea what this means, but my friend used to say it all the time.)
Better than a slap in the belly with a cold fish.
Face like a slapped arse.
Face like a dropped pie
Face like a bulldog chewing a wasp
Slick’r 'n snake shit.
Thick as two short planks.
Dumber than a bag of hammers.
Slow as molasses in January.
Colder than a whore’s heart.
Colder than a husky’s nuts in a dogsled race.
Smelling like a Kansas City cathouse.
Crazier than a shithouse rat.
As nervous as a whore in church.
“Hotter than a fresh-fucked fox in a forest fire.”
“Pretty enough to make a preacher kick a hole in a stained glass window.”
“Black as sin and bitter as an old whore.” [Said of coffee or–rather alarmingly–of tea.]