Lamp Sand Lime
This is a mega meme, created from three lesser memes.
- "RAPE HER WITH A LAMP!" - (probably) from this klerck post: 
- "Fill it with sand" - punchline from a Something Awful 'Jeff K' comic 
- "I'll eat your ass on a lime" - a misheard quote from Mike Tyson, first posted by xvdl on Wednesday, January 23 2002 at 11:09am.
However what made the Lime meme engraved in Shack culture was four days later, on the morning of Sunday January 27th 2002 the Shacknews comment system was hacked  and the text "oh and btw, I'M GONNA EAT YOUR ASS ON A LIME", a misheard qoute by Mike Tyson made a few days earlier, started to appear on the end of every post accompanied by an image of the boxer, later switching to other text and images (Screenshot 1) including Maarten Goldstein wearing the Shack famous plastic cowboy hat (Screenshot 2).
These three memes were joined into a mega meme which was popular back in the Shugashack days.
It is now commonly used IRL for Shackers to identify each other: one shacker begins the phrase ("Lamp...") and the other finishes it. It is also the inspiration for the Shacknews Crest.