Need some help

Hi there, I was looking for the comic where spike has to help twilight find a book of some sort, checks out her ass, and then they fall. I can’t find it anywhere, so if you know what I’m talking about, pleas help me out.

Was this comic per chance humanized? Because I remember an image set like that a while ago that got deleted because it violated Rule #5.2 (Spike was underaged and Twi had some panty shots?).
 
EDIT:  
Here’s a link to the forum post that describes it getting deleted, which includes a link to DeviantArt page containing the images.

Thank you so much :D exactly what I was looking for!