someone's faxing me a snickers

Dropping the kids at the pool.

In our language "sitting" is a synonym of "meeting". So in the office setting, I always say "I have an important sitting coming up".

Honk out a dirt snake

"Gotta use the sandbox"

Lay a sewer pickle

"I gotta go do some paper work" or "I need to get something down on paper" are my two go-tos

I've got shit to do

"I'm sitting on a cigar"

"I need to poo-poo in the pot-tay"

I need to go 3D print something.

i say “gotta go log out”

i do freelance work with technology, and the clients think i am going to do something work related and technical.

I gotta drop the Browns off at the Superbowl.

I'm gonna try and lose some weight

Gotta paint the town brown

Gotta curl one out

Gotta pinch a loaf

The chocolate bus honks.

Gotta make a deposit at the porcelain ATM.

My favorite is, "boss makes a dollar, I make a dime. I'll be back in awhile."

I'm gonna run for the White House

I'm gonna go drop the kids off at the pool

I find myself quoting a line from Farscape a lot:

Must...Excrete...

"Gotta see a man about a dog."

Had a coworker that would go the the bathroom and sit in there for 10 to 15 so I started calling it a "Tony ten-er."

Gotta make room for dinner

A silly Dutch one is saying you got a fax from Darmstad, which is a city in Germany but also Darm=intestines and Stad=city.

Taking the Browns to the Super Bowl

(the cleveland browns are an american football team)

"I'll be right back, gotta check if the bathroom still works"

Not exactly an answer to your question but hey what a coincidence

"Gotta go read The Hobbit" after my dad claimed he could do it in one 'sitting'.

In Dutch or Flemish at least we say: Ik moet een grote boodschap doen.

Which is a literal translation for: I have to make a big message.

I need to pinch a loaf.

Gotta drop the kids off at the pool

If I have to pee I'll say "I have to pee" if I have to shit I say "I have to go to the bathroom"

Gotta work my shift at the fudge factory.

I quote cars.

There's a rumble in the Bronx

There's big trouble in little China

The spice must flow

Gotta send teal'c through the stargate.

I need to practice the tuba.

Time to go take the Browns to the Super Bowl.