From Homestar Runner Wiki
Stooly is the trusty chair from which Strong Bad checks his emails. Although the sound of Stooly's scooting on the floor had been heard for some time, he had not been known to speak until the email the chair, however this might be the first time he does because he recently became alive due to his level of grossness (see later in this section).
Stooly is a four-legged stool with a pale yellow cushion that has been described as a "tush-cheek's dream". Nevertheless, after having been used to check well over a hundred emails, Stooly's status had declined from "cottony squish" and "pillowy fresh" to "stank". In addition, he had grown so disgusting that he began to cough, claiming that he needed a lozenge. These faults prompted Strong Bad to get a new chair, Le Restige. However, after an uncomfortable incident involving sweatpants, it appears that Strong Bad began using Stooly once again in his next email, what I want. Although Stooly was not shown on screen in that email, his return was confirmed in the subsequent email, looking old.