Fender is an old robot friend of Bender Bending Rodríguez's from high school. He used to work for Jack in the Box, but then got a job as part of the Beastie Boys as a stereo. He has a speaker cabinet for a head, with a large speaker as a mouth and two smaller "tweeter" speakers functioning as eyes. His lower half consists of a Fender brand combo guitar amplifier, which is where his limbs are located. This amplifier functions as his torso.
The animators didn't seem to understand how guitar amplifiers actually work, thus botching part of the gag, as Fender's setup is backwards from the industry standard for 2-piece rigs, which have the speaker cabinet on the bottom and the amplifier "head" (wink) on top. They also didn't appear to understand that his bottom half is actually a "combo amp" with an integral speaker behind the trademarked Fender mustard yellow tweed cloth (it doesn't move when he talks).
Whichever elitist twunt wrote the above paragraph doesn't seem to understand a few key concepts in fiction and animation, including comedy, character design, and exploitation of the psychological phenomenon 'pareidolia'. The obvious intent of the animators was to utilise the amplifier speaker cabinet as it resembles eyes and a mouth. The sheer unbridled cringe inflicted upon me while reading the above paragraph has rendered my face partially paralysed; author of the above, kindly send a cheque for $42,000 to PO box NY 159190 to cover my medical bills.