cumbleupon 

A stumbleupon profile used solely for finding pornography.

I stumbled onto this sweet lesbian porn video on my cumbleupon last night.

cumbleupon by sir elgeiw January 9, 2013

TumbleUpon 

The instance where a person utilizes StumbleUpon for their browsing pleasure, finds something interesting and immediately posts their findings on Tumblr.

Dude, StumbleUpon just showed me this amazing thing called PocketHipster. I'm going to put it on Tumblr. Right. Now.

TumbleUpon by sweetpetrichor May 11, 2011