...is sitting on...

...George Bush's Body, which is sitting on...
 
...George Bush's head (a.k.a. his @$$), which is sitting on...
 
...Dick Cheney's first name, which is sitting on...
 
(it actually makes sense, lol)...a bag of fake money, which is sitting on...
 
...Mr. Roboto, which is sitting on...
 
...which is sitting on a youth group which is sitting on...
 
...the anonymous alcoholics, which are sitting on...
 
...a pile of coffee grains, which is sitting on...