From Homestar Runner Wiki
Gooblies is Strong Sad's plush lobster, nicknamed Gooby. Attached to Gooblies is a tag displaying the letter "G". In suntan, Gooblies is held hostage by Strong Bad in order to force Strong Sad to endorse the Ab-Abber 2000. Strong Bad later attempts to sell Gooblies for $77 in garage sale, which is a reference to the email number that Gooblies debuted in.