I had to consult my local super robot/mecha fan to find out that "jig" was actually "Jeeg" and that the head in the image was his... Why Konata has his head here is anyone's guess, I suppose.

Because its funny.

Because Hiroshi transforms into Jeeg's head, and then connects to the robot components launched from Miwa's Big Shooter. Duh.

or someone took the name Steel Jeeg as "Steal" Jeeg.