a website where people share their websites and send the pages they visited to each other
Man i was on this cool as site just now!I sent it to you on stumbleupon,you got it yet?
by stevoo0011 July 27, 2006
A tool for Mozilla Firefox that is used for trolling at the speed of light.
I use stumbleupon every day! In fact, I use it a thousand times a day!
by That One Italian June 23, 2010
(N) 1. Stumbleupon is an internet sea of feminine passive-aggression, trolling and insanity. An ideal forum for internet tough guys, pretentious bitches, would be political pundits, old women and shitty poets to sound off. Members of the 'core forums' aren't well known for having much going on with respect to interpersonal skills, as is evidenced by their endless hours spent online.

2. A place for douche bags too old for 4chan to hang out.

3. A web browser utility used for trading kittens photographs, smut, and astronomical photos amongst 'friends', who are generally people you wouldn't spend a minute with in real life.
I joined Stumbleupon, but hated the experience. It's like facebook for wordy douche bags.
by Riddlze November 2, 2009
The act of being on the website stumbleupon so frequently that there need to be a term for it.
"What were you up to last night?"
"Oh nothing, just reading and stumbleuponing."
by stumbleuponer July 18, 2011
v. and n.

When using the tool, Stumbleupon on a slow work day and you have 'Stumbled' so many times that:

1. You are actually sick of the internet;

2. All the pages are beginning to look familiar;

3. You're clicking next out of habit and aren't even looking at the computer screen any more.
Roopy: Lola, you look tired and depressed.

Lola: I had a slow day at work today, so I used Stumbleupon for 6 hours straight and I might murder something if I see another Cyanide and Happiness comic strip.

Roopy: Ouch, looks like you've hit Stumbleupon Saturation Point (SSP). Go read a book for a few days, you'll feel better.
by BahumBugg April 5, 2011
When utilizing StumbleUpon (With porn topics enabled), one may hit the "Stumble" button, be distracted by a friend/barking dog/TV, and glance back at screen only to greeted by extreme acts of porn unexpectedly. Thus, provoking a noise such as, "Whoa!"

Justin: "Toby, what the hell are you yelling about?! All's well, you're just tripping man. I'm gonna get back to Stumbling...... WHOA, THERE 4 DUDES AND A GRANNY ON MY SCREEN!! STUMBLEUPON DONE GOT ME!!"
by Maddmatt4life June 17, 2011