How NOT to lock a bike?

After a couple years of walking by my bike twice a day, I noticed something funny about it...

Bike Lock Mystery: Something is wrong in this picture

Backstory
From the dust, it should be somewhat obvious that the bike hadn't been taken for a ride in a long time. The bicycle was stored in an enclosed area so while it was outside, there was some protection from the elements. And because it hadn't seen use for so long, the idea to get rid of it came up.

One major concern was if the lock still worked or not. If the U-lock didn't work, there was still a chance that the steel pad-lock connecting the chain the U-lock looped around would work. Plan F would have been to get a pair of bolt-cutters or to let it rot. That turned out not be a problem after a closer look at the bike.

See it yet?
Don't worry about the black wire chain, that thing isn't properly attached in the photo. The U-lock, however, is technically in the locked position. What exactly is it looped around though?

A bike seat?

The U-lock was attached under the seat and kept in place by the seat. Did I mention it was a fairly standard removable seat with the flip-lock thing? Still haven't gotten rid of the bike yet, but on the bright side, I won't have to get bolt-cutters if the U-lock doesn't work anymore. More shocking was the fact that the bike wasn't stolen over the past few years...

If you're wondering, I do recall making an effort to loop the U-lock around the frame and to use the wire chain around the wheels when I still cared about it.