Lay some links.
This thread caused me to remember an old men’s room grafitti:
“Here I sit, asshole hurtin’ -
just gave birth to another Albertan”
(sorry featherlou :))
Enlighten oneself
Beach a steamer
Grow a tail
Fire off a fudge round
Re: Downloading.
We had this discussion at work a few years ago, where it was pointed out that downloading is taking something from the server, while uploading is pushing something to the server.
Personally, as the king of my castle, I spend some time on my throne drafting new laws.
And don’t scream “Fire!” in a crowded bowel.
Unpack some fudge?
“I’ll be in the other office doing some paperwork.”
Yesterday I was constipated but I managed to work the problem out with pencil and paper.
Baking a Cake
You know it’s time if you’re showing turtle.
“Squeezing the cheese” was a fond one from my childhood.
“Seeing what Brown can do for me”
“Sending my chili down the Nile”
“Simmer the broth” (for diahrhea)
I personally like to say “Nature’s calling on line two.” Occasionally I’ll add “And she won’t take a message”
“Do the moonhouse two-step.” Again, hearkening back to the days of outhouses.
Giving birth to a politician.
Meditating in the porcelain throne
after several polite answers to the question “what happens when you eat Dairy/soy/wheat?”
and I am getting tired of the question I just respond with
pissing out of my ass
I’m gonna memorize this one. 
The USA version, quoted for scholarly reasons only:
Here I sit, asshole flexin’
Just gave birth to another Texan!
A hull breach is imminent, must eject the warp core!
I’ve seen “longhorn Texan”, myself.
There are several versions of this, you know. The classic couplet:
Here I sit, broken hearted;
Paid to shit but only farted.
A common riposte:
Pity me - you had your chance.
I had no dime and shit my pants!
Others I’ve seen:
Here I sit upon the pooper,
Just gave birth to a MA state trooper.
Here I sit, alack, alas!
Godzilla just came out my ass.
Here I sit, alas, alack!
I shit so much my ass turned black.
(Okay, those last two were in college campus bathrooms.)
And for completeness’ sake, one I saw in St. Petersburg that has stayed with me. (Translation mine.)
Ты не пей из унитаза.
Там бацилии и зараза.
Дёрни ручку, воду слей,
Пену сдуй - потом уж пей.
From the crapper do not drink;
The germs within infect and stink.
The handle brings the water; tug!
Blow the foam off - then you chug.