When something is totally awesome, fun, or cool it is said to be "up the butt". It is used in place of other colloquialisms such as "off the hook" and "out of control". Whenever possible, this expression should always be accompanied by making a "two thumbs-up" gesture.
This expression traces its origins to a misspoken German travelling in the US. It is common to the Big Island of Hawaii.
After a skydiver lands his friend run out to greet him and asks,
"How was the jump?"
The skydiver smiles, gives two thumbs up and replies "Up the butt!!"