Sheldon is the Tenant's Association
Penny comes in complaining that the lunch truck had moved because someone complained to the Tenants' Association. It's not allowed to part on their street anymore. Leonard first wonders who might do it and then they go to Sheldon's front door. Sheldon concurs that he made the complaint. Penny then emails the Tenants' Association as Sheldon's phone rings. Sheldon is the president and the entire association. And he tells Penny to spellcheck her emails. [ Season 11 - Episode 19 : The Tenant Disassociation]
Screenshots
