Calling another person fat is rude and disrespectful.
Dave is at work in his cubicle when he is introduced to a new coworker, Ralph who is quite obese.
Dave wants to say something helpful to Ralph.
Dave tells Ralph that their computers store a technical help guide that will explain how to do most of the job tasks.
Dave tells Ralph that since he's quite fat he might have to request a special chair from management and that he can help him do so.
Ralph is happy to hear Dave's helpful little tidbit of information and is glad he already has one helpful colleague.
Ralph is insulted that Dave called him fat and insinuated that regular chairs cannot handle his mass.